Previous studies have suggested that 14-47% of the variation in bone mineral density (BMD) can be predicted using clinical risk factors. The aim of our study was to determine, for the first time, the importance of these factors in individuals with evidence of a genetic predisposition to the disease. The subjects studied were 147 female and 86 male Caucasians, all with a family history of osteoporosis. Linear regression was used to determine whether age, height, weight, and years of reduced estrogen exposure were significant predictors of BMD. Males and females were examined separately, and BMD was measured at the hip and spine. The results show that these risk factors, known to be at work in the general population, are equally important in those with a family history of osteoporosis. It is clear, therefore, that they must be taken into account, and corrected for in genetic studies of the disease.