The yield of carcass parts as well as levels of carcass fat, moisture, and ash were measured in the 1957 Athens-Canadian Randombred Control (ACRBC) and in the Ross 308 commercial broiler, when fed diets that were representative of those being fed during 1957 and 2001. The Ross 308 was used to represent 2001 commercial broilers. Comparisons of carcass weights of the Ross 308 on the 2001 diet versus the ACRBC on the 1957 diet showed they were 6.0, 5.9, 5.2, and 4.6 times heavier than the ACRBC at 43, 57, 71, and 85 d of age, respectively. Yields of hot carcass without giblets (fat pad included) were 12.3, 13.6, 12.2, and 11.1 percentage points higher for the Ross 308 than for the ACRBC at those ages. The yields of total breast meat for the Ross 308 were 20.0, 21.3, 21.9, and 22.2% and were 8.4, 9.9, 10.3, and 9.8 percentage points higher than for the ACRBC at those ages. Yields of saddle and legs for the Ross 308 broiler were approximately 31 to 32% over the four ages and were about 1.5 to 2% higher than for the ACRBC at the different ages. The Ross 308 averaged 13.7, 15.0, 18.6, and 18.5% whole carcass fat versus 8.5, 10.6, 12.7, and 14.0% for the ACRBC at the four ages. In conjunction with previous studies, the current data show that yield of broiler carcass parts has continued to increase over time and that genetics has been the major contributor to changes in yield.