The accessory soleus muscle is infrequently found; no reports of it are available in South American literature. It is found between the tibia and the soleus muscle in the distal leg. It may be misdiagnosed as a hemangioma, lipoma or sarcoma. It may be the cause of functional disorder such as varus or equino-varus. Among 254 dissections performed in young adults of both sexes and different ethnic origin we found only 2 accessory soleus muscles, both in males. One originated from the soleus muscle and was inserted in the superior aspect of the "calcaneo", in front of the "tendon calcaneo". The other originated from the anterior fascia of the soleus muscle and was inserted on the medial aspect of the "calcaneo". The clinical significance of the accessory soleus muscle is related to the presence of pain or functional disorders.