BACKGROUND: During the last three decades, the resistance of S. pneumoniae to penicillin has been rapidly increasing in many parts of the world, especially in Korea. To characterize the clinical features and epidemiology of penicillin-resistant S. pneumoniae (PRSP) infections in the community and hospital, as well as to investigate the possible spread of resistant clone, we performed the antimicrobial susceptibility tests, pulsed filed gel electrophoresis (PFGE) and penicillin-binding protein (PBP) profile analysis of PRSP isolates. METHODS: A total 48 PRSP isolates from patients who visited or were admitted to Korea University Guro hospital during the period form July 1998 to June 1999 were studied. Anitimicrobial susceptibility tests for 48 isolates were performed with microbroth dilution method to determine the minimal inhibitory concentration of 11 antibiotics. 39 isolates and 35 isolates were subjected to PFGE and PBP profile analysis, respectively to investigate the genetic relatedness between PRSP isolates. RESULTS: Pneumonia was most common site of infection in the community and the hospital as 50%. There were no significant differences of clinical features and prognosis between community and hospital isolates. But, patients with serious underlying diseases had poor prognosis despite of acquisition site. High level penicillin resistance were observed in 69%, multi-drug resistance were 64.6% of isolates. PFGE showed that 13 of 29 community acquired infection were identical PFGE pattern but not that of 23F Spanish clone. There were various PFGE patterns were observed from community and hospital acquired infection isolates. Some of them were existed in both. PBP profiles showed more diverse, even if in isoaltes of the same PFGE pattern. CONCLUSOIN: In our study, high level penicillin resistance and multi-drug resistance were observed in PRSP clinical isolates. No clinical and prognostic differeces were observed between community and hospital acquired infections. Molecular epidemiology study were suggest the there were various genotypes of PRSP within our society. Some of them were observed in the hospital and community. Therefore, there was an evidence of communication of PRSP clones between the community and hospital.