OBJECTIVE: Evaluate articular cartilage by magnetic resonance imaging (MRI) T2 * mapping within the distal femur and proximal tibia in adolescents with juvenile osteochondritis dissecans (JOCD). DESIGN: JOCD imaging studies acquired between August 2011 and February 2019 with clinical and T2 * mapping MRI knee images were retrospectively collected and analyzed for 31 participants (9F/22M, 15.0 +/- 3.8 years old) with JOCD lesions in the medial femoral condyle (MFC). In total, N = 32 knees with JOCD lesions and N = 14 control knees were assessed. Mean T2 * values in four articular cartilage regions-of-interest (MFC, lateral femoral condyle (LFC), medial tibia (MT), and lateral tibia (LT)) and lesion volume were measured and analyzed using Wilcoxon-rank-sum tests and Spearman correlation coefficients (R). RESULTS: Mean +/- standard error T2 * differences observed between the lesion-sided MFC and the LFC in JOCD-affected knees (28.5 +/- 0.9 95% confidence interval [26.8, 30.3] vs 26.3 +/- 0.7 [24.8, 27.7] ms, P = 0.088) and between the affected- and control-knee MFC (28.5 +/- 0.9 [26.8, 30.3] vs 28.5 +/- 0.6 [27.1, 29.9] ms, P = 0.719) were nonsignificant. T2 * was significantly increased in the lesion-sided MT vs the LT for the JOCD-affected knees (21.5 +/- 0.7 [20.1, 22.9] vs 18.0 +/- 0.7 [16.5, 19.5] ms, P = 0.002), but this same difference was also observed between the MT and LT in control knees (21.0 +/- 0.6 [19.7, 22.3] vs 18.1 +/- 1.1 [15.8, 20.4] ms, P = 0.037). There was no significant T2 * difference between the affected- and control-knee MT (21.5 +/- 0.7 [20.1, 22.9] vs 21.0 +/- 0.6 [19.7, 22.3] ms, P = 0.905). T2 * within the lesion-sided MFC was not correlated with patient age (R = 0.20, P = 0.28) or lesion volume (R = 0.06, P = 0.75). T2 * values were slightly increased near lesions in later-stage JOCD subjects but without statistical significance. CONCLUSIONS: T2 * relaxations times were not significantly different from control sites in the articular cartilage overlying JOCD lesions in the MFC or adjacent MT cartilage in early-stage JOCD.