In the upper limb the communications between the median and the ulnar nerves are relatively common and have been described in different point throughout it, in or below the elbow. The purpose of this study is to determine the incidence, type, topography of the anastomoses between median and ulnar nerves in forearm and hand. A total of 14 cadavers were used for the study in the laboratory of Morphology of the University of Pamplona. Communication between the median and ulnar nerves was observed in 1 of 28 upper limbs. The communicating branch was originates from the branch of the median nerve to the flexor digitorum superficialis muscle. Other anastomoses were not found in the upper limb. Knowledge of these anatomical variations allows a more appropriate diagnostic and procedures of disorders of the peripheral nerves in the upper limb.