Cefuroxime axetil (CAE) is a prodrug of cefuroxime which is suitable for oral administration, being hydrolysed by non-specific esterases to release cefuroxime (CXM) into the bloodstream. This study was performed in four centres in the UK to investigate the efficacy and safety of CAE administered at a dosage of either 250 mg t.d.s. or 500 mg b.d. for the treatment of community-acquired lower respiratory tract infections. Of the 69 clinically assessable patients, 33 out of 34 (97%) patients on 250 mg t.d.s. and 31 out of 35 (89%) on 500 mg b.d. were cured or improved. Positive bacteriology was obtained from 43 (61%) of the pretreatment sputum samples, of which 35 (51%) were assessable: the pathogen was eradicated from 14 out of 16 (88%) on 250 mg. t.d.s. and 16 out of 19 (84%) on 500 mg b.d. The most common infecting organism was H. influenzae, accounting for 49% of the isolates; 81% of these were eradicated. There were 3 superinfections, all in the higher dosage group, one with Serratia liquifaciens which was resistant to CXM. CAE was generally well tolerated, with only 9 patients experiencing adverse events, most of which were gastrointestinal. None of these cases was sufficiently serious to require symptomatic treatment and in only one case was treatment stopped early. There was no difference in the incidence of side-effects in the two dosage groups. CAE, at a dose of 250 mg t.i.d. or 500 mg b.d., was demonstrated to be a safe and effective treatment for lower respiratory tract infections in the community.