In human anatomy, the third trochanter is a bony projection occasionally present on the proximal femur near the superior border of the gluteal tuberosity.

[1] A structure of minor importance in humans, the incidence of the third trochanter varies from 17 to 72% between ethnic groups and it is frequently reported as more common in females than in males.

It may function as (1) a reinforcement mechanism for the proximal femoral diaphysis in response to increased ground reaction force and (2) to increase the attachment surface area for the gluteal musculature and thereby providing greater efficiency of contracture.

[2] Studying fossils of Ardipithecus ramidus (a chimpanzee–human last common ancestor candidate), Lovejoy et al. 2009 noted that in this species—as well as in Proconsul, Nacholapithecus, and Dryopithecus (Miocene primates)—homologs to the third trochanter and the hypotrochanteric fossa[5] are present while both traits are absent in extant apes.

They concluded that the hominid morphotype is primitive and the femoral shape of apes is derived contrary to what was previously thought.