Free, autogenous periosteal grafts from the medial metaphysis of the proximal tibia have been used to reconstruct full thickness cartilage defects of the articular surfaces of the knee joint. If there was a bone defect, it was initially filled with cancellous bone graft. The method is illustrated by six patients, three with acute traumatic patellar defects and three with local sclerotic osteochondritis of the medial femoral condyle. The latter had loose fragments unsuitable for fixation and single excision would have left a large and deep defect. The grafts have given satisfactory results, 14 to 59 months after the procedures. Clinical grading of the defects has been monitored by radiographs with arthroscopy of two knees and CT scan of one knee.