The main objective of this study was to characterize carcasses of slaughtered bulls in order to develop a carcass grading standard. Two hundred thirty carcasses were evaluated morphometrically for conformation and fatness. The breeds were Holstein, Limousin, Charolais, and crossbred beef bulls. Carcass measurements recorded at the slaughterhouse were: carcass length, hind leg perimeter, carcass depth, hind leg length and thickness. Hot carcass weight, fat thickness at the sixth rib and kidney fat weight were recorded. Principal component analysis and cluster analysis were performed to characterize carcasses. Analysis of variance was also performed to determine significant difference between the four classes of carcasses identified in this study. Results showed four groups of carcasses described as follows: (1) low weight and small size carcasses, (2) average weight and large size carcasses, (3) heavy weight and small size carcasses, (4) heavy weight and large size carcasses. In conclusion, weight and length of the carcass can be used as the main measurements to establish a carcass grading grid in Tunisia.