Nutritional metabolic bone disease (NMBD) is one of the most frequently observed pathological conditions in herpetoculture. To develop guidelines for NMBD prevention in growing veiled chameleons (Chamaeleo calyptratus), 56 hatchlings were divided into 6 groups [group UV, with UVB exposure; group No: no supplements; group CaAUV: with calcium (Ca), vitamin A, UVB; group CaA: with Ca, vitamin A; group CaADUV: with Ca, vitamin A, cholecalciferol, UVB; and group CaAD, with Ca, vitamin A, cholecalciferol] and reared for 6 mo on locust-based diets. The nutrient composition of the locusts' diet and the locust-based diet for the chameleons was determined. The diagnosis included the detailed description of clinical findings, histopathology, measurements of serum Ca, 25-hydroxycholecalciferol (25-OHD(3)), liver 25-OHD(3), vitamin A, bone mineral density, and bone mineral concentration. Chameleons that received no dietary supplementation of Ca, vitamin A, and cholecalciferol developed NMBD. When Ca and vitamin A were supplemented, the chameleons did not develop NMBD, independently of additional UVB and dietary cholecalciferol. The best prevention for NMBD was achieved by chameleons that received locusts gut-loaded with 12% Ca and dusted with 250,000 IU/kg (75 mg/kg) vitamin A and 25,000 IU/kg (0.625 mg/kg) cholecalciferol plus provision of long (10 h/d), low irradiation exposure (3-120 μW/cm(2)) to UVB. Chameleons that were fed diets low in vitamin A, cholecalciferol, and Ca were diagnosed with fibrous osteodystrophy. We noticed an interaction of vitamin A and cholecalciferol supplementation in the storage of vitamin A in the liver and formation of colon calcifications. From these findings, recommendations for the rearing of juvenile chameleons were derived.