In an attempt to analyze the characteristics of domestic pathogenic strains of S. pneumoniae, the basic epidemiological charactristics of pathogenic strains such as their serotypes and frequency of penicillin resistance, and pattern of chromosomal DNA from PFGE(pulsed-field gel electrophoresis) were observed. For this study,56 strains of S. pneumoniae isolated from inpatients and outpatients in the four domestic university hospitals were collected from January to December in 1998. Among those strains, a total of 56 pathogenic strains from blood(39 isolates), cerebrospinal fluid(8 isolates) and other specimen(9 isolates) were selected and isolated. The penicillin resistance frequency of those 56 strains was identified with disk diffusion method with 66.1％. From the invasive strains, predominant serotypes were isolated in the order of 19F(12.5％), 23F(10.7%), 14(10.7%) and 9V(10.7％), totalling 45 percent. This experiment also used PFGE patterns to compare the correlations among genetic subtypes in several serotypes. The DNA fragments digested with Sma I and Apa I were resolved by PFGE. The PFGE patterns digested with Sma I were better than Apa I for analysis. In the DNA fragments digested with Sma 1, PFGE analysis of 56 S. pneumoniae isolates showed 25 different patterns. As a result, serotype was on the whole correlated to PFGE pattern on the ground that each different PFGE pattern by serotype was observed. This study can be utilized not only fur the study of incidence trend of domestic pneumococcal diseases but also as a useful basic data for the development of identification tool and treatment.