The weights of normal brains obtained at autopsy from Royal Perth Hospital and the Perth City Coroner's Department during the last decade were reviewed. The analysis involved 728 Caucasian and 63 Aboriginal brains. The ages ranged from 21 to 90 years, but the Aboriginal group were generally younger than the Caucasian. All brains were examined in detail by the Neuropathology Department, Royal Perth Hospital. Brains with any significant macroscopic or microscopic abnormality were excluded from the analysis. Statistical comparisons between the brain weights of the Caucasians and Aboriginal subpopulations show that Aboriginals had smaller brains than Caucasians. Even after correcting for body height, Caucasian brain weights were significantly heavier than Aboriginal brain weights. Results also showed that men had significantly higher mean brain weights than women of the same age. There was a tendency for the mean brain weight of both men and women to decrease in later life, particularly in the eighth and ninth decades. Ho et al. (1980) showed in their analysis of 1261 brains in the USA, that brain weight decreases from white males to black males to white females to black females. The tendency in both this and the present investigation for the non-Caucasians to have smaller brains than the Caucasians warrants further study.