An isolated avulsion fracture involving the femoral origin of the medial head of the gastrocnemius muscle without an associated muscular, meniscal, or ligamentous injury is extremely rare. We report a case of a 14-year-old male wrestler who presented with a radiographically occult avulsion fracture of the medial gastrocnemius tendon sustained during competition. To our knowledge, this is the first case to describe a mechanism of injury as well as to report a return to competition after non-operative management.