The bone mineral content (BMC) of the mid-shaft radius was measured in 446 rural Gambian and 349 British women aged 18-80+ years using single-photon absorptiometry. The two groups of women differed substantially in habitual calcium intake, calcium requirements for reproduction, physical activity and incidence of minimal-trauma fractures. The relationships of BMC with bone width (BW) and with body weight and height were explored using stepwise multiple regression analysis. The pattern of BMC with age was similar in The Gambia and Britain; BMC increased slightly to a peak at the end of the fourth decade followed by a decrease of about 30% between 40 and 70+ years. Gambian women had significantly lower BMC than British women of the same age (-5.6%, P less than 0.001) but after adjusting for weight, height and BW, the BMC of Gambian women was shown to be slightly higher than that of British women (+2.1%, P less than 0.05).