We have previously reported that children with constitutionally delayed growth (CDG) have significantly lower spinal bone mineralization than children with familial short stature (FSS). The aim of the present study was to evaluate whether the decreased bone mineralization in children with CDG also affects the radius, which has a lower bone turnover than the spine. To avoid the possibility of size-related artifacts in the assessment of bone mineral data, data were corrected for bone and body size. Radial bone mineral content (RBMC) and radial bone mineral density (RBMD) were measured by dual energy X-ray absorptiometry (Hologic QDR 1000/w) in 56 short prepubertal children aged 5-11 years. All children had height below the 10th percentile for chronological age (CA), and bone age (BA) less than 10 years, 29 of them with clinical diagnosis of CDG and 27 of them with FSS. The mean (+/- SD) RBMD was significantly lower in the children with CDG than in the FSS group (0.361 +/- 0.035 vs 0.385 +/- 0.033 g/cm2, p<0.05). RBMC was significantly lower in CDG than in FSS, when multiple regression analysis was performed by using radial scanned bone area (RSBA), body weight and height, sex and BA as independent variables (p = 0.03). These data indicate that the decreased bone mineralization in children with CDG also affects peripheral bone, and that this finding is not due to bone or body size artifacts.