The objective of this research was to use developing Angus heifer real-time ultrasound records to estimate genetic parameters and calculate carcass EPD for external 12-13th rib fat (FAT), rump fat thickness (RFAT), ribeye area (REA), and % intramuscular fat (%IMF). Heritability estimates are all of a moderate level (> .40) and are higher than the estimates determined previously with bull-only ultrasound data. Genetic correlations are generally of the same magnitude and same sign as previously reported with the bull-only ultrasound data. Angus breeders need to be alerted to the fact that developing heifers can be scanned to accurately predict carcass merit in steer-mate half-sibs. The results of this research indicate that the heifer data may be more accurate than the half-sib yearling bulls findings because the heritability estimates from the heifer data are higher than those estimated from the yearling bull data.