We evaluated the durability of autologous chondrocyte transplantation grafts in 61 patients treated for isolated cartilage defects on the femoral condyle or the patella and followed up for a mean of 7.4 years (range, 5 to 11). Durability was determined by comparing the clinical status at the long-term follow-up with that found 2 years after the transplantation. After 2 years, 50 of the 61 patients had good or excellent clinical results, and 51 of 61 had good or excellent results at 5 to 11 years later. Grafted areas from 11 of the patients were evaluated with an electromechanical indentation probe during a second-look arthroscopy procedure (mean follow-up, 54.3 months; range, 33 to 84); stiffness measurements were 90% or more of those of normal cartilage in eight patients. Eight of twelve 2-mm biopsy samples taken from these patients showed hyaline characteristics with safranin O staining and a homogeneous appearance in polarized light. Three fibrous and eight hyaline biopsy specimens stained positive to aggrecan and to cartilage oligomeric matrix protein. Hyaline-like specimens stained positive for type II collagen, and fibrous, for type I collagen. Autologous chondrocyte transplantation for the treatment of articular cartilage injuries has a durable outcome for as long as 11 years.