diff --git a/main/src/com/google/refine/expr/functions/math/Abs.java b/main/src/com/google/refine/expr/functions/math/Abs.java
new file mode 100644
index 000000000..c661cf544
--- /dev/null
+++ b/main/src/com/google/refine/expr/functions/math/Abs.java
@@ -0,0 +1,63 @@
+/*
+
+Copyright 2010, Google Inc.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+    * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,           
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY           
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+package com.google.refine.expr.functions.math;
+
+import java.util.Properties;
+
+import org.json.JSONException;
+import org.json.JSONWriter;
+
+import com.google.refine.expr.EvalError;
+import com.google.refine.grel.ControlFunctionRegistry;
+import com.google.refine.grel.Function;
+
+public class Abs implements Function {
+
+    public Object call(Properties bindings, Object[] args) {
+        if (args.length == 1 && args[0] != null && args[0] instanceof Number) {
+            return Math.abs(((Number) args[0]).doubleValue());
+        }
+        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects a number");
+    }
+
+    public void write(JSONWriter writer, Properties options)
+        throws JSONException {
+    
+        writer.object();
+        writer.key("description"); writer.value("Returns the absolute value of a number");
+        writer.key("params"); writer.value("number d");
+        writer.key("returns"); writer.value("number");
+        writer.endObject();
+    }
+}
diff --git a/main/src/com/google/refine/grel/ControlFunctionRegistry.java b/main/src/com/google/refine/grel/ControlFunctionRegistry.java
index 3a1945d8e..f137310a1 100644
--- a/main/src/com/google/refine/grel/ControlFunctionRegistry.java
+++ b/main/src/com/google/refine/grel/ControlFunctionRegistry.java
@@ -59,6 +59,7 @@ import com.google.refine.expr.functions.booleans.Or;
 import com.google.refine.expr.functions.date.DatePart;
 import com.google.refine.expr.functions.date.Inc;
 import com.google.refine.expr.functions.date.Now;
+import com.google.refine.expr.functions.math.Abs;
 import com.google.refine.expr.functions.math.Ceil;
 import com.google.refine.expr.functions.math.Exp;
 import com.google.refine.expr.functions.math.Floor;
@@ -214,6 +215,7 @@ public class ControlFunctionRegistry {
         registerFunction("round", new Round());
         registerFunction("floor", new Floor());
         registerFunction("ceil", new Ceil());
+        registerFunction("abs", new Abs());
         registerFunction("mod", new Mod());
         registerFunction("max", new Max());
         registerFunction("min", new Min());