The purpose of this study was to evaluate the clinical and microbiological effects of minocycline-loaded polycaprolactone strip on periodontal disease. Ten patients with probing depth (deeper than 5mm) were tested. Of the two periodontal pockets selected from each patient, one randomly selected pocket was treated by the insertion of 30% minocycline-loaded polycaprolactone sttip as the experimental group and the other with a minocycline-free polycaprolactone strip as the control group. All groups were examined by clinical and microbiological methods. 1. Plaque index scores, gingival index scores and sulcular bleeding index scores in both group were significantly reduced from the baseline to 2 weeks. Plaque index scores of experimental group and sulcular bleeding index scores of control group tended to be progressively reduced in all experimental periods. 2. Probing depth amounts in both group were significantly reduced from 4 weeks to 8 weeks. 3. Attachment loss amounts in both group shows no singnificant differences in time. Attachment loss amounts in experimental group tended to be less than those in control group. 4. The number of cocci in both groups were significantly increased in all experimental periods, but that of the non-motile rods were significantly reduced from 2 weeks in experimental group, and from 4 weeks in control group, that of the motile rods were reduced from 4 weeks in experimental group and from 1 week in control group. The number of spirochetes were reduced from I week during all experimental period in experimental group, but there was no changes in control group.