Management of juvenile osteochondritis dissecans is controversial. The purpose of this study was to evaluate the functional and radiographic outcomes of transarticular arthroscopic drilling for isolated stable, juvenile osteochondritis dissecans lesions of the medial femoral condyle with an intact articular surface after 6 months of nonoperative management had failed. We reviewed 30 affected knees in 23 skeletally immature patients (mean age, 12.3 years; range, 8.5 to 16.1) at an average follow-up of 3.9 years (range, 2.0 to 7.2). Functional outcome was determined using the Lysholm score and radiographic outcome was determined using lesion size, and the radiographic score of Rodegerdts and Gleissner. There was significant improvement in the mean Lysholm score (from 58 to 93). There was significant improvement in the mean lesion size on anteroposterior (4.5 +/- 5.8 mm decrease) and lateral (8.4 +/- 8.1 mm decrease) radiographs. There was also significant improvement in the mean radiographic score (from 3.0 to 1.9). Radiographic healing was achieved in all patients at an average of 4.4 months after drilling (range, 1 to 11 months). Linear regression analysis revealed that younger age was an independent, multivariate predictor of Lysholm score improvement. There were no apparent surgical complications.