There are many controversies in ability of articular cartilage to heal full thickness defect. Generally, it is reported that full thickness defects of articular cartilage filled with organizing hematoma and granulation tissues, which converted to chondroid tissues. It is clear that the size of defect was related to the repair of articular cartilage. Though cartilagenous material fills the defect and restores the surface continuity, it may undergo degeneration, and lead to localized focus of osteoarthritis. Multiple drilling through subchondral bone could be a kind of treatment in articular cartilage defect. Author conducted an experiment for the full thickness defect of articular cartilage in rabbit. After multiple drilling of articular cartilage, the repair of defect was examined histologically until eighth week. Results were as followings ; l. At lst. week, the defect was repaired by fibrovascular proliferation and granulation tissue. 2. At 3rd. week, hyaline cartilage consisted of normal chondrocyte was formed. 3. At 8th. week, subchondral plste was regenerated completely. 4. All defects that were less than 3 mm. in diameter were healed. More repairs were observed in case with the wider defects if the defects were within 3mm. in diameter. 5. The metachromasia was observed with toluidine blue stain. The reformed cartilage shows slight purple(Grade II) to moderate purple(Grade III) at third week and near normal (Grade IV) at fourth week. In conclusion, multiple drilling may be an effective method of treatment in articular cartilage defect. It is considered that multiple drilling with a 3mm. Steinmann pin may be the most convenient and effective method of the cartilage healing.