Thirty-four patients, most of them immunocompromised, with severe hospital-acquired infections, including septicaemia, respiratory tract and complicated urinary tract infections were treated with ceftazidime 1-2 g intravenously 8-hourly. Twenty-six patients were cured or improved (76%). The most common pathogens were Enterobacteriaceae and Pseudomonas aeruginosa; Gram-positive organisms were isolated from nine patients. Failure were observed in eight patients (24%), four of them had infections caused by resistant organisms, one had infection with Ps. aeruginosa which became resistant during therapy. Superinfection occurred in 11 patients (32%). Mean peak serum levels after 1 g intravenously were 86.2 +/- 30.3 mg/l; after 2 g intravenously 151.6 +/- 52.2 mg/l. The half-life of serum elimination was 1.8-1.9 h, 2 h in patients with liver function disorders and 3 h in patients with renal impairment. Side effects were mild. Ceftazidime is useful in treating Gram-negative infections, but the gaps in its spectrum, the high rate of superinfection and emergence of resistance are matters of concern.