The efficacy of meropenem was compared to that of the combination of tobramycin plus clindamycin (T/C) in a multiinstitutional clinical trial of treatment for patients suffering intraabdominal infection. Among the 177 patients enrolled and randomized, 127 were clinically evaluable and 86 were microbiologically evaluable. Analysis of data on an intent-to-treat basis for all randomized patients and on the basis of a successful outcome (absence of any infection) for clinically evaluable patients failed to detect any difference in efficacy between the two treatments. Infection was cleared in 92% of meropenem- and 89% of T/C-treated clinically evaluable patients. Eradication of pathogens also was similar in the two treatment groups. Overall, adverse drug experiences were comparable between the two treatment groups, with the exception of an increase in serum creatinine level (which occurred more frequently in patients receiving T/C). Meropenem appears to be efficacious for the treatment of intraabdominal infections.