Aims: To obtain data on the bone mineral density state in a group of patients with neuroþbromatosis-1 spinal curves, to search for possible accompanying changes in the bone mineral turnover and to determine whether the genotypes at three known polymorphic loci are associated with a decreased bone mineral density in scoliotic patients with neuroþbromatosis. Methods: As part of the preoperative evaluation, dual X-ray absorptiometry was used to assess the bone mineral density of the lumbar spine in 12 patients with neuroþbromatosis- 1, supplemented by laboratory blood/urine investigations. In the pilot study, genetic polymorphisms were tested in the VDR gene, the COL1A1 gene and the OER gene by standard PCR technique. Results: A signiþcant decrease in bone mineral density of lumbar spine was measured. An inverse relation was suggested between the severity of scoliosis and the lumbar spine Z-scores. A three-fold prevalence of the homozygous polymorphism (CC) over the heterozygous form (Cc) of the COL1A1 gene was observed in the nonscoliotic NF1 patients as compared to the patients with scoliosis, presenting with an almost equal distribution in this genotype. Conclusions: The bony tissue abnormality observed intraoperatively in neuroþbromatosis-1 patients may be described as a diminution of the axial bone mineral density. The increased prevalence of the CC genotype of the COL1A1 gene in nonscoliotic NF patients appears to have a possible protective role against spinal deformities in NF1 patients. The evaluation of bone mineral density in the course of the preoperative planning is proposed in neuroþbromatosis-1.