Background: An osteochondral lesion of the talus is a relatively rare disorder of the ankle. While a number of treatment options have been reported, it appears to be difficult to manage all lesions with a single approach. We evaluated the indications for and the results of arthroscopic drilling for the treatment of an osteochondral lesion of the talus.Methods: Eighteen ankles (seventeen patients) with a symptomatic osteochondral lesion of the talus were examined. The ages of the patients ranged from ten to seventy-eight years (mean, 28.0 years) at the time of the operation, and the patients were followed postoperatively for two to 9.5 years (mean, 4.6 years). After the continuity of the cartilage overlying the lesion and the stability of the lesion had been confirmed, arthroscopic drilling was performed with use of a Kirschner wire that was 1.0 to 1.2 millimeters in diameter. A cast was not applied postoperatively, and full weight-bearing was allowed six weeks after the procedure.Results: The clinical result was good for thirteen ankles and fair for five; all ankles had improvement. Twelve of the thirteen ankles that were in patients who were less than thirty years old had a good result. In contrast, only one of the five ankles in patients who were fifty years old or more had a good result. Thus, the clinical results tended to be better for younger patients. Improvement was seen radiographically in fifteen ankles. However, the three ankles in patients who were more than sixty years old were found to have no improvement on radiographic examination. Analysis of the group of patients who had a history of trauma revealed that the mean interval between the injury and the operation was 6.3 months for the three ankles that had a good radiographic result and 11.3 months for the six that had a fair result. Thus, the radiographic results tended to be better when the interval between the injury and the operation was shorter.Conclusions: Arthroscopic drilling for the treatment of medial osteochondral lesions of the talus does not require osteotomy of the medial malleolus or postoperative immobilization; thus, the procedure is less invasive than other types of operative treatment for the condition and it allows early resumption of daily activities and sports. On the basis of the results in this study, we believe that the procedure is effective and useful in young patients, especially those who have not yet had closure of the epiphyseal plate. A specific indication for the procedure is an early lesion with only mild osteosclerosis of the surrounding talar bone, continuity of the cartilaginous surface, and stability of the osteochondral fragment.