To assess cartilage quality with anatomical location and extent of osteoarthritis (OA), magnetic resonance imaging (MRI) of the knee joint from rhesus monkeys was performed. MRI measurements--T1 and T2 relaxation times, proton density and cartilage thickness were taken from 8 equal segments of articular cartilage volumes extending from anterior to posterior edge of 1 mm sagittal slices. To grade the severity of OA in each quadrant of the knee joint a modified Mankin score was applied on the histological sections. Our results suggest that MR relaxation times and proton density values vary with the severity of osteoarthritis.