Community-acquired pneumonia (CAP) is a serious disease frequently treated empirically, which required the selection of an antibiotic that covers all common pathogens and achieves good pulmonary concentrations. The availability of intravenous (i.v.) formulations may also be helpful, permitting i.v./p.o. sequential therapy. From January 1992 to December 1997 we treated 290 CAP patients with clarithromycin (CL) 500 mg BID, first given i.v. in 250 or 500 ml of saline solution and then switched after 4-5 days to the same dosage given p.o. Of these 290 patients 163 were males (98 smokers) and 127 were females (41 smokers); 87 were over 65 years old and 203 had concomitant diseases (mainly cardiovascular), 172 patients were admitted after unsuccessful therapy (122 cephalosporins and 48 penicillins). Diagnosis was made based on clinical and radiological findings, therapy was initiated prior to microbiological diagnosis. Clinical and radiological improvement was achieved by 261/290 patients (90%) within 10-15 days. Mild adverse events occurred in 11 patients. This results indicate that CL is effective and safe: its antimicrobial spectrum and pharmacokinetic profile, the possibility of i.v./p.o. sequential administration, make it an ideal antibiotic for the treatment of CAP.