Background: Some of the risk factors for osteoporosis population include: chronic immobilisation, insufficient dietary supply of calcium and vitamin D, decreased physical activity and long-term pharmacological treatment (glucocorticoids, anticonvulsant drugs). In disabled children and adolescents, the negative impact of these factors may cumulate to considerably impair the quality of life. Objectives: The aim of our study was to assess the vitamin D status and bone mineral density in children with chronic neurological syndromes. Material and Methods: A total of 34 children between 3 and 18 years of age were examined: 9 children with muscular dystrophy, 17 with cerebral palsy and 8 with lumbar myelomeningocele. All the subjects underwent the following assessments: measurement of the concentration of the hepatic metabolite of vitamin D and total body less head and/or lumbar spine densitometry by dual energy X-ray absorptiometry (DEXA). Low bone mass or low bone mineral density was diagnosed if the Z-score value was found to be equal to or below −2.0. Results: Indications for the above tests were chronic immobilisation or motor activity restriction, and—in 10/34 children—femoral or vertebral fracture. Vitamin D deficiency (81%). Low bone mass on densitometry was demonstrated in 27/34 and osteoporosis in 10/34 subjects (Z-score ≤ −2.0). Conclusion: Bone densitometry should be included in the standard of care for children with chronic neurological syndromes, and early detection of low bone mass should be an indication for treatment with calcium and vitamin D.