The purpose of this study was to document outcomes following microfracture for full-thickness cartilage defects of the knee in adolescents. Our hypothesis was that patients aged 18 years or less would have excellent outcomes and function following microfracture of full-thickness knee articular cartilage defects. This study was approved by the Institutional Review Board. Patients < 19 years old with full-thickness knee articular cartilage defects treated with microfracture between January 1992 and June 2008 were identified. Surgical, demographic data, Lysholm score, Tegner activity scale, and patient satisfaction were collected prospectively. A total of 26 patients (14 females, 12 males) met inclusion criteria. Average age was 16.6 years (range: 12-18.9 years). Ninety-six percent of lesions were patellar (37%) or femoral condyle defects (medial 26%, lateral 33%). Minimum 2-year follow-up was obtained in 22/26 patients (85%) with average follow-up of 5.8 years (range: 2.0-13.3 years). Average postoperative Lysholm score was 90 (range: 50-100). Median Tegner scale was 6 (range: 2-10). Median patient satisfaction with outcome was 10 (range: 1-10). Lysholm correlated with Tegner scale (rho = 0.586; p = 0.011) and patient satisfaction (rho = 0.70; p = 0.001). Average postoperative Lysholm score in males was 93 and 86 in females (p = 0.22). One patient underwent revision microfracture. This study showed that adolescent patients who underwent microfracture for treatment of full-thickness knee chondral defects demonstrated increased activity levels and excellent function following surgery.