diff --git a/stdnum/ar/__init__.py b/stdnum/ar/__init__.py
index 999da35b..e9a097b9 100644
--- a/stdnum/ar/__init__.py
+++ b/stdnum/ar/__init__.py
@@ -22,3 +22,4 @@
 
 # provide vat as an alias
 from stdnum.ar import cuit as vat
+from stdnum.ar import cbu as cbu
diff --git a/stdnum/ar/cbu.py b/stdnum/ar/cbu.py
new file mode 100644
index 00000000..4ea5b6ff
--- /dev/null
+++ b/stdnum/ar/cbu.py
@@ -0,0 +1,96 @@
+# cbu.py - functions for handling Argentinian CBU numbers
+# coding: utf-8
+#
+# Copyright (C) 2016 Luciano Rossi
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""CBU (Clave Bancaria Uniforme).
+
+CBU it s a code of the Banks of Argentina to identify the accounts
+of their clients.
+
+>>> validate('2850590940090418135201')
+'2850590940090418135201'
+>>> validate('285059094009041')
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> validate('A850590940090418135201')
+Traceback (most recent call last):
+    ...
+InvalidFormat: ...
+>>> validate('2810590940090418135201')
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...
+"""
+
+from stdnum.exceptions import *
+from stdnum.util import clean
+
+
+def compact(number):
+    """Convert the number to the minimal representation. This strips the
+    number of any valid separators and removes surrounding whitespace."""
+    return clean(number, ' -').strip()
+
+
+def calc_check_digit(number):
+    """Calculate the check digit."""
+    ponderador = '9713'
+    bloque_valor = number[:-1]
+    bloque_digito = int(number[-1])
+    largo_valor = len(bloque_valor)
+    suma = 0
+    digito_ponderador = 3
+
+    for count in range(largo_valor):
+        indice = -1 - count
+        valor = int(bloque_valor[indice])
+        ponderacion = int(ponderador[digito_ponderador])
+
+        suma += valor * ponderacion
+        if digito_ponderador > 0:
+            digito_ponderador = digito_ponderador - 1
+        else:
+            digito_ponderador = 3
+
+    bloque_suma = 10 - (suma % 10)
+    digito = int(str(bloque_suma)[-1])
+    return digito == bloque_digito
+
+
+def validate(number):
+    """Checks to see if the number provided is a valid CBU."""
+    number = compact(number)
+    if len(number) != 22:
+        raise InvalidLength()
+    if not number.isdigit():
+        raise InvalidFormat()
+    if not calc_check_digit(number[:8]):
+        raise InvalidChecksum()
+    if not calc_check_digit(number[8:]):
+        raise InvalidChecksum()
+    return number
+
+
+def is_valid(number):
+    """Checks to see if the number provided is a valid CBU."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False