In order to prevent metabolic bone disease in growing captive-bred marabou storks (Leptoptilos crumeniferus), three hatchlings were exposed twice a day for 30 min each time to ultraviolet-B (UVB) radiation. During their first 35 days of life, body weights were monitored weekly, and blood was collected to determine total calcium, phosphorus, 25(OH)cholecalciferol, and 1.25(OH)₂ cholecalciferol plasma levels. Data were compared with those obtained from two marabou stork nestlings that were raised before, without being exposed to UVB. These two birds developed metabolic bone disease, while the UVB-exposed birds developed into healthy adult animals. Plasma chemistry data obtained in this study demonstrate that nestling marabou storks produce vitamin D₃ under the influence of UVB radiation. The absence of clinical metabolic bone disease in the nestlings that received UVB compared to the nestlings that were raised with the same diet without UVB radiation and that developed MBD demonstrates the importance of UVB radiation for normal development in this species.