The supernumerary fascicles of abductor digiti minimi muscle have been implicated in vascular and nerve compression. During routine dissection of an old male cadaver we observed an anomalous muscle was found to take it's origin from the antebrachial fascia and flexor retinaculum, traversed ulnar canal (Guyon's) superficial to ulnar vessels and nerves to reach the proximal part of abductor digiti minimi. The anomaly is one of a kind. Its course through Guyon's canal could be a cause for Guyon's canal syndrome. It was innervated by the ulnar nerve