Three Korean rapidly progressive periodontitis patient (R.P.P.) were examined for the isolation and identification of black-pigmented Bacteroides and Bacteroides gingivalis in the subgingival plaque. Black-pigmented Bacteroides and Bacteroides gingivalis were recovered from all three R.P. patients and the predominant isolates were Bacteroides intermedius followed by Bacteroides gingivalis. The B. gingivalis isolated from subgingival plaque of rapidly progressive periodontitis patients were Gram-negative pleomorphic rods and each produced brown to black colonies on blood agar plate supplemented with 5% rabbit 5ug/ml haemin, 0.5ug/ml of menadione and 40ug/ml of Kanamycin. The B. gingivalis isolated were fermented none of Glucose, Sucrose, Lactose, Esculin and Cellobinose and produced indole. Isolation and identification of Bacteroides gingivalis in Korean R.P. patients can be contributed to the research on the pathogenesis of Korean periodontal disease.