diff --git a/core/src/main/java/feign/RequestTemplate.java b/core/src/main/java/feign/RequestTemplate.java
index d1c276f7f5..86dc730698 100644
--- a/core/src/main/java/feign/RequestTemplate.java
+++ b/core/src/main/java/feign/RequestTemplate.java
@@ -13,11 +13,7 @@
  */
 package feign;
 
-import static feign.Util.CONTENT_LENGTH;
-import static feign.Util.UTF_8;
-import static feign.Util.checkNotNull;
 import feign.Request.HttpMethod;
-import feign.template.BodyTemplate;
 import feign.template.HeaderTemplate;
 import feign.template.QueryTemplate;
 import feign.template.UriTemplate;
@@ -25,19 +21,12 @@
 import java.io.Serializable;
 import java.nio.charset.Charset;
 import java.util.AbstractMap.SimpleImmutableEntry;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Iterator;
-import java.util.LinkedHashMap;
-import java.util.LinkedHashSet;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.Map.Entry;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
+import static feign.Util.*;
 
 /**
  * Request Builder for an HTTP Target.
@@ -51,7 +40,7 @@ public final class RequestTemplate implements Serializable {
 
   private static final Pattern QUERY_STRING_PATTERN = Pattern.compile("(?<!\\{)\\?");
   private final Map<String, QueryTemplate> queries = new LinkedHashMap<>();
-  private final Map<String, HeaderTemplate> headers = new LinkedHashMap<>();
+  private final Map<String, HeaderTemplate> headers = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
   private String target;
   private boolean resolved = false;
   private UriTemplate uriTemplate;
@@ -73,7 +62,6 @@ public RequestTemplate() {
    *
    * @param target for the template.
    * @param uriTemplate for the template.
-   * @param bodyTemplate for the template.
    * @param method of the request.
    * @param charset for the request.
    * @param body of the request, may be null
@@ -691,7 +679,7 @@ public RequestTemplate headers(Map<String, Collection<String>> headers) {
    * @return the currently applied headers.
    */
   public Map<String, Collection<String>> headers() {
-    Map<String, Collection<String>> headerMap = new LinkedHashMap<>();
+    Map<String, Collection<String>> headerMap = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
     this.headers.forEach((key, headerTemplate) -> {
       List<String> values = new ArrayList<>(headerTemplate.getValues());
 
diff --git a/core/src/test/java/feign/LoggerTest.java b/core/src/test/java/feign/LoggerTest.java
index 6f8ac7d688..a8dcb6ca71 100644
--- a/core/src/test/java/feign/LoggerTest.java
+++ b/core/src/test/java/feign/LoggerTest.java
@@ -76,16 +76,16 @@ public static Iterable<Object[]> data() {
               "\\[SendsStuff#login\\] <--- HTTP/1.1 200 OK \\([0-9]+ms\\)")},
           {Level.HEADERS, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://localhost:[0-9]+/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
               "\\[SendsStuff#login\\] <--- HTTP/1.1 200 OK \\([0-9]+ms\\)",
               "\\[SendsStuff#login\\] content-length: 3",
               "\\[SendsStuff#login\\] <--- END HTTP \\(3-byte body\\)")},
           {Level.FULL, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://localhost:[0-9]+/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ",
               "\\[SendsStuff#login\\] \\{\"customer_name\": \"netflix\", \"user_name\": \"denominator\", \"password\": \"password\"\\}",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
@@ -161,14 +161,14 @@ public static Iterable<Object[]> data() {
               "\\[SendsStuff#login\\] <--- ERROR SocketTimeoutException: Read timed out \\([0-9]+ms\\)")},
           {Level.HEADERS, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://localhost:[0-9]+/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
               "\\[SendsStuff#login\\] <--- ERROR SocketTimeoutException: Read timed out \\([0-9]+ms\\)")},
           {Level.FULL, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://localhost:[0-9]+/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ",
               "\\[SendsStuff#login\\] \\{\"customer_name\": \"netflix\", \"user_name\": \"denominator\", \"password\": \"password\"\\}",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
@@ -223,14 +223,14 @@ public static Iterable<Object[]> data() {
               "\\[SendsStuff#login\\] <--- ERROR UnknownHostException: robofu.abc \\([0-9]+ms\\)")},
           {Level.HEADERS, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://robofu.abc/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
               "\\[SendsStuff#login\\] <--- ERROR UnknownHostException: robofu.abc \\([0-9]+ms\\)")},
           {Level.FULL, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://robofu.abc/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ",
               "\\[SendsStuff#login\\] \\{\"customer_name\": \"netflix\", \"user_name\": \"denominator\", \"password\": \"password\"\\}",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
@@ -285,14 +285,14 @@ public static Iterable<Object[]> data() {
               "\\[SendsStuff#login\\] <--- ERROR UnknownHostException: sna%fu.abc \\([0-9]+ms\\)")},
           {Level.HEADERS, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://sna%fu.abc/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
               "\\[SendsStuff#login\\] <--- ERROR UnknownHostException: sna%fu.abc \\([0-9]+ms\\)")},
           {Level.FULL, Arrays.asList(
               "\\[SendsStuff#login\\] ---> POST http://sna%fu.abc/ HTTP/1.1",
-              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] Content-Length: 80",
+              "\\[SendsStuff#login\\] Content-Type: application/json",
               "\\[SendsStuff#login\\] ",
               "\\[SendsStuff#login\\] \\{\"customer_name\": \"netflix\", \"user_name\": \"denominator\", \"password\": \"password\"\\}",
               "\\[SendsStuff#login\\] ---> END HTTP \\(80-byte body\\)",
diff --git a/core/src/test/java/feign/RequestTemplateTest.java b/core/src/test/java/feign/RequestTemplateTest.java
index 220a94ef84..e7b7034084 100644
--- a/core/src/test/java/feign/RequestTemplateTest.java
+++ b/core/src/test/java/feign/RequestTemplateTest.java
@@ -16,13 +16,10 @@
 import static feign.assertj.FeignAssertions.assertThat;
 import static java.util.Arrays.asList;
 import static org.assertj.core.data.MapEntry.entry;
+import static org.junit.Assert.*;
 import feign.Request.HttpMethod;
 import feign.template.UriUtils;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.Map;
+import java.util.*;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
@@ -323,6 +320,27 @@ public void spaceEncodingInUrlParam() {
         .isEqualTo("/api/ABC%20123?key=XYZ%20123");
   }
 
+  @Test
+  public void useCaseInsensitiveHeaderFieldNames() {
+    final RequestTemplate template = new RequestTemplate();
+
+    final String value = "value1";
+    template.header("TEST", value);
+
+    final String value2 = "value2";
+    template.header("tEST", value2);
+
+    final Collection<String> test = template.headers().get("test");
+
+    final String assertionMessage = "Header field names should be case insensitive";
+
+    assertNotNull(assertionMessage, test);
+    assertTrue(assertionMessage, test.contains(value));
+    assertTrue(assertionMessage, test.contains(value2));
+    assertEquals(1, template.headers().size());
+    assertEquals(2, template.headers().get("tesT").size());
+  }
+
   @Test
   public void encodeSlashTest() {
     RequestTemplate template = new RequestTemplate().method(HttpMethod.GET)