OBJECTIVE: Aluminum has known neurotoxicity and may impair short-term bone health. In a randomized trial, we showed reduced neurodevelopmental scores in preterm infants who were previously exposed to aluminum from parenteral nutrition solutions. Here, in the same cohort, we test the hypothesis that neonatal aluminum exposure also adversely affects long-term bone health, as indicated by reduced bone mass. METHODS: Bone area (BA) and bone mineral content (BMC) of lumbar spine, hip, and whole body were measured with dual radiograph absorptiometry in 13- to 15-year-olds who were born preterm and randomly assigned standard or aluminum-depleted parenteral nutrition solutions during the neonatal period. RESULTS: Fifty-nine children (32% of survivors) were followed. Those who were randomly assigned to standard parenteral nutrition solution had lower lumbar spine BMC, apparently explained by a concomitant decrease in bone size. In nonrandomized analyses, children who were exposed to neonatal aluminum intakes above the median (55 μg/kg) had lower hip BMC (by 7.6% [95% confidence interval 0.21–13.8]; P = 0.02), independent of bone (or body) size. CONCLUSIONS: Neonates who are exposed to parenteral aluminum may have reduced lumbar spine and hip bone mass during adolescence, potential risk factors for later osteoporosis and hip fracture. These findings need confirmation in larger, more detailed studies. Nevertheless, given our previous finding of adverse developmental outcome in these individuals and the sizeable number of contemporary infants who undergo intensive neonatal care and are still exposed to aluminum via parenteral feeding solutions, the potential adverse long-term consequences of early aluminum exposure now deserve renewed attention.