In a double-blind prospective study, 180 patients admitted to hospital with acute purulent exacerbations of chronic bronchitis were treated for seven days with twice daily 1 g intramuscular injections of either cefodizime or cefotaxime. Sputum cultures performed before, during and immediately after treatment showed complete eradication of the infection in 89/90 given cefodizime and 86/90 receiving cefotaxime. Some symptomatic Pseudomonas aeruginosa superinfections occurred with each agent. During the follow-up week, recurrences or reinfections after apparent clearance occurred in 15 patients given cefodizime and in 21 receiving cefotaxime. Pharmacokinetic studies in blood showed mean Cmax values of 50.8 mg/l for cefodizime and 36.5 mg/l for cefotaxime, corresponding values in the sputum being 1.61 and 0.62 mg/l. Mean AUC values in both blood and sputum were 2 1/2- to 3-fold higher for cefodizime. Some features suggested better performance by cefodizime than by cefotaxime, but the clinical results were not statistically significantly different.