Second molar length and body weight are used to test the correlation between tooth size and body size in living Hominoidea. These variates are highly correlated (r = 0.942,p<0.001), indicating that tooth size can be used in dentally unspecialized fossil hominoids as one method of predicting the average body weight of species. Based on tooth size, the average body weight ofAegyptopithecus zeuxis is estimated to have been between 4.5 and 7.5 kg, which is corroborated by known cranial and postcranial elements. Using Radinsky's estimates of brain size, the encephalization quotient (EQ) forAegyptopithecus was between 0.65 and 1.04. A similar analysis forProconsul africanus yields a body weight between 16 and 34 kg, and an EQ between 1.19 and 1.96.