In an open, randomized, multicenter comparative trial 141 patients with acute, purulent exacerbations of chronic bronchitis were treated with either 2 tablets with 500 mg Cefuroxime (as Cefuroxime axetil)* or 3 tablets containing 500 mg Amoxicillin plus 125 mg Clavulanic acid per day. After an average of 9.3 days of therapy the infections were completely cured in 72 and 65% of the patients, respectively, and in further 23 and 32% a significant clinical improvement was achieved. Bacteriological examination of patients' sputum showed streptococci, staphylococci, Hemophilus influenzae, E. coli and klebsiellae being the predominant pathogens. After therapy nearly complete erradication of the bacterials was found in both groups of patients. Cefuroxime axetil and Amoxicillin/Clavulanic acid are both effective in the treatment of acute exacerbations of chronic bronchitis. The compliance enhancing twice daily dosing regimen of Cefuroxime axetil can be regarded as an advantage over Amoxicillin/Clavulanic acid that has to be administered three times a day due to the shorter half-lives.