The sensitivities of clinical strains of obligate anaerobic bacteria, isolated from the periodontal pouches of patients with generalized periodontitis, to antibiotics, quinolone drugs, and metronidasole were studied. The minimal suppressing concentration (MSC90) of ciprofloxacin, norfloxacin, and antibiotics gramicidin C, eritromicin, lincomycin, levomicetin, and trichopol for sensitive strains of Porphyromonas, peptostreptococci, and fusobacteria ranged from 5 to 10 mg/ml. Among the bacteria and actinomyces studied the highest percentage of resistant strains was noted for abactal and tarivid, and the minimal for gramicidin C and eritromicin. Actinomyces were little sensitive to quinolone derivatives.