Communications between nerves are relatively common, and individual variations in their anatomical organization have been described. Knowledge of the prevalence of such variations is necessary when establishing the diagnosis of neuropathies and surgical landmarks. In this study, 64 anterior forearm regions of cadavers of blacks and whites of both sexes, were dissected to examine the communication between the median and ulnar nerves (Martin-Gruber anastomosis). This anastomosis was found in five cases (7.8%), one of which was bilateral. There were no significant gender or racial differences in the incidence of this connection. The anastomosis showed secondary branches in two cases, and ran posteriorly to the ulnar artery in three cases, and advanced anteriorly to the flexor digitorum profundus muscles in all cases. Despite the low incidence of Martin-Gruber anastomosis in Brazilians observed here, the importance of an adequate investigation of these connections needs to be underscored. Understanding the existence of this variation, its location and its possible presentation is important for correct patient assistance.