Ninety patients with serious infections, including 61 with septicaemia, pneumonia, peritonitis or meningitis, were treated with ceftazidime. Of these patients, 85.6% were clinically cured (73.3%) or improved (12.2%) by the antibiotic. In this study, 57.7% had infections due to Escherichia coli (24.7%), Klebsiella sp. (14.5%) and Pseudomonas sp. (18.5%). Two children with cystic fibrosis and Pseudomonas pneumonia and an adult with Legionella pneumonia responded well to ceftazidime treatment. Seventy patients had fever before treatment and most of them became apyrexial in less than 2 to 3 days. Ceftazidime was given either intramuscularly (42 patients) or intravenously (48 patients), in a dose of 1 g tds in 71 patients or 2 g tds in severe infections in 11 patients, or reduced to suit the renal function (7 patients) or in paediatric doses (2 children). Blood ceftazidime levels were measured in eight patients with normal renal function. The average level one hour post dosing was 45.2 mg/l and the average trough level was 8.1 mg/l. Six patients were suffering from variable degrees of renal insufficiency (serum creatinine 149 to 668 mmol/l). Their average blood level 1 h post-dosing was 68.8 mg/l. In a patient with meningitis, the CSF level was 2.4 mg/l 2 h after a 1 g dose. These levels are several times the ceftazidime MIC values for most clinical bacterial isolates. Ceftazidime is a valuable and safe alternative to aminoglycoside therapy.