The present study was done to evaluate the antibacterial effects of $Minoclin^R$ which was localally delivered on the $Gore-tex^R$ barrier membrane in the guided tissue regeneration(GTR) therapy for treatment of human furcal defects. Beneath the membranes. the antibiotics were applied for 1 week and then changed with new one. The $Minoclin^R$ was removed out one week later. 6 weeks after the GTR therapy. No systemic antibiotics were administered except for oral mouthrinses with chlorhexidines. 2 weeks and 6 weeks following the membrane therapy, the bacterial samples were examined for periodontopathic microorganisms. The results indicated that the locally delivered $Minoclin^R$ successfully inhibited the growth of periodontopathic organisms. This results might be further applied in the subgingival plaque control regimen in the GTR procedure, especialy in patients who is contraindicated for oral administration of systemic antibiotics