Growth parameters of term born children at one year of age are predictive of bone mass in adults (Cooper et al, J Bone Miner Res 1995;10:940). No data exist regarding preterm birth and adult bone mass. The objective of this preliminary study was to establish significant determinants of bone mass in adolescents who were born prematurely. The study population comprised 15 Caucasian infants born <1500g between 1978-1982 who were graduates of a one year follow-up study. Measures of gestational age 30.8±2.9 wk, weight(Wt) 1.2±0.2 kg and length (Lg) 39.9±2.3 cm at birth and Wt and Lg measures at term, 6 and 12 mo corrected age were obtained from the one year follow-up data base. Measures at 16.6±1.6 years include: Wt, height(Ht) and whole body (WB), total lumbar (L) 1-4 and femoral (F) neck, trochanter and total bone mineral content (BMC) and density (BMD) as measured by dual energy x-ray absorptiometry (4500W, Hologic). Wt and Lg at birth and during the first year of life were compared with current measures using a two-tailed Pearson correlation coefficient. No significant relationships were detected between Lg at birth, term or 6 mo corrected age and current age. Wt at 6 mo, but not birth or term, was significantly associated with higher trochanter BMD 6 mo (r=0.62, P<0.01). Wt 9.3±1.6 kg at 12 mo, but not Lg 73.5±1.5 cm, was significantly associated with adolescent Wt(r=0.92, P<0.001), Ht (r=0.81, P<0.01), and WB (r=0.63, P<0.05), F trochanter (r=0.65, P<0.05), and F neck BMC (r=0.63, P<0.05); no significant associations with L1-4 BMC or any measure of BMD were observed. These data suggest that catch-up weight growth by one year corrected age in infants born <1500 g establishes growth tragectory and also supports development of greater bone mass in adolescence. In contrast, since attainment of adult weight and height is positively associated with development of peak bone mass, it is speculated that infants who do not achieve catch-up weight growth by one year of age will not achieve growth trajectories and will consequently have lower peak bone mass in adulthood.