Objectives:The aim of the study was to assess the efficacy of intra-articular administration of MgSO4 in an osteochondral lesion model created experimentally in rabbits. Methods: A total of 22 New Zealand rabbits were used in the study for the creation of a standard osteochondral lesion in the right femur medial condyles. Twice a week for periods of 6 and 8 weeks, MgSO4 (0.1ml) at a dose of 500µg was injected intra-articularly to the magnesium group and 0.1ml saline solution to the control group. At 2 weeks after the final injection, all the animals were euthanised. An osteotomy was performed to include the region where the osteochondral defect was formed, and each sample was placed in 10% formalin solution. Morphological evaluation and scoring was performed. The samples were stained with hematoxylin-eosin and safranin-O, then histopathological evaluation and scoring was performed. Results: The histopathological scores of the Mg-6-week group were determined to be significantly higher than those of the control-6week and control-8-week groups (p=0.025, p=0.012). The macroscopic scores of the Mg-6-week group were determined to be significantly higher than those of the control-6-week group (p=0.003). In the histological examination, the osteochondral defect area of the Mg groups showed intense healing from hyalin cartilage whereas in the control group, healing was seen to be weighted towards fibrous cartilage. Conclusion: The intra-articular administration of MgSO4 in the osteochondral lesion model created experimentally in rabbits was determined to have made a positive contribution to histopathopathological and morphological healing.