In an open, multicentre, randomised study, the efficacy and safety of meropenem monotherapy as adjuvant antibiotic therapy in the surgical management of intra-abdominal infection was compared with that of the combination of cefotaxime and metronidazole. A total of 160 hospitalised adult patients with intra-abdominal infection requiring surgery were treated intravenously with either meropenem 1 g every 8 h (by bolus injection or infusion; n = 77) or cefotaxime 2 g and metronidazole 500 mg every 8 h (n = 83). Clinical and bacteriological responses to antibiotic therapy were assessed at the end of treatment and at 2-4 weeks' follow-up after treatment. The clinical response rates at the end of treatment and follow-up were 91% and 96%, respectively, for meropenem and 100% and 97%, respectively, for cefotaxime plus metronidazole. The bacteriological response rates were 90% and 93%, respectively, for meropenem and 92% at both time points for cefotaxime plus metronidazole. Both treatments were well tolerated. In this study, meropenem monotherapy was effective and as well tolerated as cefotaxime plus metronidazole. Meropenem monotherapy should, therefore, prove a useful alternative to standard combination therapy for the empirical treatment of intra-abdominal infections.