A study of data from 12 states in the Food Safety Inspection Service's Residue Violation Information System was conducted to describe patterns of violative chemical residues in US beef during 1991, 1992, and 1993. In 1991, 3,249 violative residues were found in 2,734 carcasses in the 12 states included in the study. In 1992, 3,132 violative residues were found in 2,813 carcasses, and in 1993, 2,317 violative residues were found in 2,051 carcasses. During each of the 3 years, the Calf Antibiotic and Sulfonamide Test and Swab Test On Premises projects detected most of the violative residues, and producers/independent growers and dairy farms were recorded as the responsible sources for most of the violations. Also, most of the animals found to have violative residues were bob calves and culled cows. In bob calves, neomycin was the most frequently identified violative chemical, followed by tetracycline, gentamicin, oxytetracycline, and penicillin. In culled cows, penicillin was the most frequently identified violative chemical and was the chemical most frequently found in combination with other chemicals in cows with multiple violative residues. Distribution patterns of violative chemical residues by slaughter class and residue type varied among the 5 Food Safety Inspection Service regions. These specific regional characteristics support the need for customized intervention, education, assessment, and prevention programs.