The collagen crosslinks deoxypyridinoline and pyridinoline are indices of mature collagen breakdown and reflect increased bone turnover. Urinary levels were found to be significantly raised in a group of 59 women with knee OA compared to 110 female controls from the general population. Levels of the crosslinks correlated significantly with X-ray grade of all subjects including women from the general population with mild, often asymptomatic, disease. These correlations were not diminished after adjustment for age and weight.