The investigation was performed with 9 strains of B. fragilis isolated from pregnant women in their 38th week of pregnancy, strain IPLE 323 obtained from France, strains BE17 and BE61 obtained from Netherlands and a strain 210 isolated from a case of appendicitis. The strains were identified by indirect immunofluorescence method and by API 32 ATB test. Ability to adhere to epithelium of oral cavity and vaginal mucosa and sheep and human erythrocytes was investigated. Susceptibility to antibiotics was also measured. It was found that strains isolated from vagina easier adhere to epithelial cells of vagina than to cheek epithelium and erythrocytes.