Anatomical variations are typically more common in the extensor compartment of the forearm, but uncommon in the flexor compartment. The presence of such anatomical anomalies is not usually noticed until the normal functions of an individual become hindered, or when these anomalies become a surgical problem. During routine dissection curriculum, we encountered a rare finding of bilateral Gantzer muscles in a cadaver. We describe the relationship between the Gantzer muscle and anterior interosseous nerve syndrome. Keywords: anterior interosseous nerve, anterior interosseous nerve syndrome, compartment syndromeSingapore Med J 2013; 54(5): e102-e104