Yield of saleable beef was predicted in 4 genotypes of bullocks (Hereford, Brahman, Brahman x Hereford and Simmental x Hereford). Simple and multiple regression equations were used to determine how well 4 fat thickness measurements (12th rib and rump measurements SC3 SC5 and SC7) individually, with or without the inclusion of hot side weight, foreshanks weight and short cut tongue weight predicted the yields of saleable beef. Each of the 4 fat thickness measurements (alone) predicted percentage yield of saleable beef with low r.s.d.'s at the means. The regression coefficients for the 4 fat thickness measuring sites were negative and significant in the Hereford, Brahman and Brahman x Hereford groups. In the Simmental x Hereford cattle, the regression coefficients for the rump sites (SC3, SC5 and SC7) were positive but significant only in SC5 which had the lowest r.s.d. (1.56%) of all sites. Twelfth rib fat thickness, with a common regression coefficient for all 4 genotypes (P<0.01) and an r.s.d. of 1.81%, was the next most useful fat thickness measurement. The addition of hot side weight improved the prediction of percentage saleable beef yield at the SC3 and SC5 sites, but not in the pure-bred Brahman bullocks. For populations that include British, European and Bos indicus cattle and their crosses, SC5 fat thickness (alone) was the best determinant of percentage yield of saleable beef. Neither quadratic analyses nor the addition of foreshanks weight or short-cut tongue weight to the fat thickness measurements improved the accuracy of linear regression in any of the 4 genotypes. The errors in prediction of percentage yield of saleable beef (0.28-0.67%) attributable to incorrect rump site location (of up to 4.0 cm) are unlikely to jeopardise the commercial value of yield of saleable beef predicted from measurements made on the rump. Whilst the Brahman and Brahman x Hereford cattle produced high-yielding carcasses for the Japanese chilled beef market and the Simmental x Hereford cattle, by judicious management could equal this yield, carcass yields of the Hereford cattle were about 4-5% lower at all levels of fat thickness. The ability of Hereford cattle to satisfy this market, economically, is seriously questioned.