Minocline Strip(MS), a local drug delivery developed as a controlling means for microoragnisms in gingival wound and periodontitis, was implanted in the gingiva of experimental animals. The toxic effects and biodegradation of MS were studied in respect to pathological changes induced in gingival tissue. The experimental animals treated with MS had not showed significant difference in symptom, body weights, feed and water intake, and blood analysis throughout 150 days of experimental period, but revealed significantly increased values of total WBC counts and AST (SGOT) on the 7th day, compared with controls. The treated animals revealed petechial hemorrhage and severe edema accompanying degeneration and necrosis of damaged muscle fibers around the surgical wound, but no local inflammatory reaction and concerned lesions were found. The implanted MS became encapsulated by thin connective tissue, and its size and color diminished gradually according to the experimental term. The MS-like material appeared in the nearby lymphatics on the 110th day. The implated MS remained as fine granular particles or disappeared on the 130th day, and the decrease of its volume and density were variable depending on each individual. These results indicate that long-term implantation of MS may not produce inflammation or toxic effects, and eventually lead to complete biodegradation.