diff --git a/doc/conf/LSattribute/check-data.docbook b/doc/conf/LSattribute/check-data.docbook
index 011a9b83..43583211 100644
--- a/doc/conf/LSattribute/check-data.docbook
+++ b/doc/conf/LSattribute/check-data.docbook
@@ -60,6 +60,7 @@ règles.</para>
 &conf-LSattribute-check-data-mimetype;
 &conf-LSattribute-check-data-nonzero;
 &conf-LSattribute-check-data-nopunctuation;
+&conf-LSattribute-check-data-numberOfValues;
 &conf-LSattribute-check-data-numeric;
 &conf-LSattribute-check-data-password;
 &conf-LSattribute-check-data-rangelength;
diff --git a/doc/conf/LSattribute/check_data/LSattribute-check_data.entities.xml b/doc/conf/LSattribute/check_data/LSattribute-check_data.entities.xml
index 0010bfa5..afae6232 100644
--- a/doc/conf/LSattribute/check_data/LSattribute-check_data.entities.xml
+++ b/doc/conf/LSattribute/check_data/LSattribute-check_data.entities.xml
@@ -15,6 +15,7 @@
 <!ENTITY conf-LSattribute-check-data-minlength SYSTEM "minlength.docbook">
 <!ENTITY conf-LSattribute-check-data-nonzero SYSTEM "nonzero.docbook">
 <!ENTITY conf-LSattribute-check-data-nopunctuation SYSTEM "nopunctuation.docbook">
+<!ENTITY conf-LSattribute-check-data-numberOfValues SYSTEM "numberOfValues.docbook">
 <!ENTITY conf-LSattribute-check-data-numeric SYSTEM "numeric.docbook">
 <!ENTITY conf-LSattribute-check-data-password SYSTEM "password.docbook">
 <!ENTITY conf-LSattribute-check-data-rangelength SYSTEM "rangelength.docbook">
diff --git a/doc/conf/LSattribute/check_data/numberOfValues.docbook b/doc/conf/LSattribute/check_data/numberOfValues.docbook
new file mode 100644
index 00000000..bd59769f
--- /dev/null
+++ b/doc/conf/LSattribute/check_data/numberOfValues.docbook
@@ -0,0 +1,25 @@
+<sect4 id="config-LSattribute-check-data-numberOfValues">
+  <title>numberOfValues</title>
+  <para>Cette règle vérifie que le nombre de valeurs de l'attribut est comprise entre les limites
+  passées en paramètre.</para>
+
+<variablelist>
+<title>Paramètres de configuration</title>
+
+<varlistentry>
+  <term>min</term>
+  <listitem>
+    <simpara>Nombre minimum de valeurs (paramètre optionnel).</simpara>
+  </listitem>
+</varlistentry>
+
+<varlistentry>
+  <term>max</term>
+  <listitem>
+    <simpara>Nombre maximum de valeurs (paramètre optionnel).</simpara>
+  </listitem>
+</varlistentry>
+
+</variablelist>
+
+</sect4>
diff --git a/src/includes/class/class.LSformRule_numberOfValues.php b/src/includes/class/class.LSformRule_numberOfValues.php
new file mode 100644
index 00000000..687405e1
--- /dev/null
+++ b/src/includes/class/class.LSformRule_numberOfValues.php
@@ -0,0 +1,88 @@
+<?php
+/*******************************************************************************
+ * Copyright (C) 2021 Easter-eggs
+ * https://ldapsaisie.org
+ *
+ * Author: See AUTHORS file in top-level directory.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+******************************************************************************/
+
+/**
+ * Check the number of values of the attribute against min/max limits
+ *
+ * @author Benjamin Renard <brenard@easter-eggs.com>
+ */
+class LSformRule_numberOfValues extends LSformRule {
+
+  // Validate values one by one or all together
+  const validate_one_by_one = False;
+
+  /**
+   * Validate value
+   *
+   * @param string $values The value to validate
+   * @param array $options Validation options
+   * @param object $formElement The related formElement object
+   *
+   * @return boolean true if the value is valide, false if not
+   */
+  public static function validate($value, $options=array(), &$formElement) {
+    $max_values = LSconfig :: get('params.max', null, 'int', $options);
+    $min_values = LSconfig :: get('params.min', null, 'int', $options);
+    if(is_null($max_values) && is_null($min_values)) {
+      LSerror :: addErrorCode('LSformRule_01',array('type' => 'numberOfValues', 'param' => _('max (or min)')));
+      return;
+    }
+    if (!is_null($max_values) && !is_null($min_values) && $max_values < $min_values) {
+      LSerror :: addErrorCode('LSformRule_numberOfValues_01');
+      return;
+    }
+
+    $count = count($value);
+    if (!is_null($min_values) && $count < $min_values)
+      throw new LSformRuleException(
+        getFData(
+          ngettext(
+            'At least one value is required.',
+            'At least %{min} values are required.',
+            $min_values
+          ),
+          $count
+        )
+      );
+
+    if (!is_null($max_values) && $count > $max_values)
+      throw new LSformRuleException(
+        getFData(
+          ngettext(
+            'Maximum one value is allowed.',
+            'Maximum %{max} values are allowed.',
+            $count
+          ),
+          $max_values
+        )
+      );
+    return True;
+  }
+
+}
+
+/**
+ * Error Codes
+ **/
+LSerror :: defineError('LSformRule_numberOfValues_01',
+___("LSformRule_numberOfValues: Parameter max could not be lower than parameter min.")
+);