Lumbar spinal bone mineral density (BMD) was measured in 40 preterm infants by dual-energy X-ray absorptiometry (DXA). During the first several months of life, their BMD was considerably lower than that of normal term infants and the osteopenia was more pronounced in the more preterm and smaller infants. Weak (inverse) correlations were found between the BMD and urinary calcium/creatinine or tubular phosphorus reabsorption ratio. Rickets-like changes in the forearm bones did not predict the greater spinal osteopenia. Follow-up study was performed in 10 preterms. In 3 of the 4 who underwent the last DXA between 8 and 12 months, BMD had improved remarkably. Our present study shows the potential of DXA for the assessment and management of osteopenia of prematurity.