Serious infections in paediatric patients pose some unique challenges to clinicians. Children represent a dynamic group of patients in whom there are age-related changes as well as age-related alterations in the biodisposition of various antimicrobial agents. In infants and children with serious infections multidrug therapy is generally employed. This occurs because most antibiotic therapy in these patients is initiated and continued on an empiric basis and few, if any, of the currently available agents may be employed confidently as monotherapy. When the agents currently available are compared on a pharmacokinetic and pharmacodynamic basis the carbapenems emerge as close to ideal for the treatment of serious infections in infants and children. Imipenem is the only member of this group currently available. It lacks paediatric labelling in the USA and its efficacy has not been compared directly with that of antibiotic regimens commonly employed in children. Meropenem is a new carbapenem currently under evaluation of the treatment of moderate to severe infections in children and adults. In 2 multicentre, randomised evaluations of the treatment of a variety of infections including lower respiratory tract infections, urinary tract infections, intra-abdominal infections, infections of the skin and skin structures, and septicaemia, the efficacy and safety of meropenem monotherapy were compared with those of cefotaxime-based regimens. Meropenem had an overall clinical efficacy rate of 98% compared with a rate of 95% for cefotaxime-based regimens. Neither regimen was associated with any significant clinical or laboratory adverse events. The carbapenem, meropenem, appears to be a reasonable choice for empiric therapy in infants and children with serious infections. Meropenem monotherapy has been evaluated and has been found to be as well tolerated and as effective as cefotaxime-based regimens in these patients.