Thirty-six urological patients (21 male, 15 female) aged 21 to 83 years with complicated and/or hospital-acquired urinary tract infections due to sensitive bacteria were treated with ceftazidime intravenously with a daily dose of 2 g bd over 5 to 17 days. Twenty-seven patients were followed for 1 to 4 weeks after therapy. Cure was observed in 41%, reinfection in 33% and relapse in 26% of the patients. Eradication of the original pathogen occurred in 74%. Five patients showed minor side effects: diarrhoea (2), nausea (1), rash (1), headache (1). No signs of renal, hepatic or haematological toxicity were observed. A pharmacokinetic study was performed in 13 elderly patients aged 63 to 83 years on day 1 of treatment and in 6 volunteers aged 24 to 32 years following administration of 2 g of ceftazidime as short intravenous infusion. The mean serum half life in 12 patients 2.9 h significantly higher than in volunteers (1.75 h). Serum concentrations in patients on day 7 of treatment, however, showed no accumulation when treated with a dosage of 2 g bd.