Eighty-one patients with 116 osteoarthritic knees were seen by the author at the University College Hospital (UCH), Ibadan in six years. Below the age of 50 the disease was significantly commoner among Nigerians than Caucasians; 39.5% of our patients were less than 50 years old, compared with 1.1% of Caucasians. In contrast with the latter group, trauma was apparently an insignificant predisposing factor of knee degeneration in our patients. In some cases osteoarthritis was associated with severe valgus deformity in rather young patients, suggesting a probable causal relationship. Multiple joint osteoarthritis was significantly less common in Nigerians than in Caucasians.