To better define the role that the lateral meniscus plays in stabilizing the knee, a study was made of twenty-six patients who had an uncomplicated lateral meniscectomy between 1972 and 1977. Patients with any degree of ligament instability, cruciate or collateral, prior to lateral meniscectomy were eliminated from the study. Also eliminated were any patients with roentgenographic evidence of degenerative arthrits, osteochondritis dissecans, or loose bodies. Only patients whose operative reports stated that the articular cartilage of the lateral compartment was either grossly normal or showed Grade-1 chondromalacia (less than one centimeter in diameter and only softening of the cartilage) at the time of surgery were included in the review. The meniscal lesions included bucket-handle tears, horizontal cleavage tears, and multiple linear defects. No grossly cystic menisci were included in the study. Two menisci demonstrated cystic degenerative changes on histological section. In sixteen patients some degree of ligament instability developed. The longer the interval between injury to the meniscus and its excision, the less satisfactory the result. Only fifteen (54 per cent) of the patients reported satisfactory results, and twenty lost some motion of the knee. We concluded that stability of the knee joint is a multifactorial problem, in which the lateral meniscus certainly plays an important part.