Cefoperazone was given to 33 surgical patients who had bacterial infections. A dose of 1 to 2 g bid was administered intravenously for an average of 8.2 days. The overall satisfactory response rate (which includes excellent and good responses) was 79%: 83% in 18 cases of peritonitis and/or intra-abdominal abscesses. 75% in 8 cases of hepatobiliary infections: 100% in 5 cases of skin and soft tissue infections; and 0 in 2 cases of sepsis. The satisfactory response rates according to the isolated organisms were: 11 of 15 Escherichia coli, 15 of 18 streptococci (including 4 of 6 enterococci) 3 of 6 Pseudomonas aeruginosa. 3 of 4 staphylococci 2 of 3 Proteus species, and 3 of 3 Klebsiella pneumoniae. No side effects were observed and there were no abnormal laboratory findings.