Three cases are reported in which anomalous muscles in the lower extremities simulated soft-tissue tumors to such a degree that surgical exploration was performed in two. In two cases the soleus accessorius muscle appeared bilaterally as a mass anteromedial to the Achilles tendon, being large on one side and small on the other. In one of these cases, the larger muscle was surgically explored on the basis of a presumptive diagnosis of hemangioma. In the other case, the nature of the lesion was recognized without exploration. In the third instance a popliteal mass was the manifestation of an anomalous hamstring muscle. The correct diagnosis was strongly suspected before operation but surgical exploration was performed none the less because of the possibility of a malignant soft-tissue neoplasm.