Bacteremia may occur after disruption of the oral mucous membrane, particularly after dental treatment. 18 mentally handicapped patients who underwent dental treatment with general anesthesia were included in our study. None of the patients had general illnesses or received antibiotic protection. From each patient several blood samples were drawn aseptically during dental treatment and cultured. The majority of aerobic bacteria recovered belonged to Streptococcus sp and Gemella sp., anaerobic bacteria mainly belonged to Porphyromonas gingivalis and Peptostreptococcus sp. Resistance of the isolated bacteria to penicillin as well as to oxacillin, erythromycin and Co-trimoxazole was substantial. The highest resistance rate could be shown against fucidic acid.