AIMS: Assessing disabilities in children is essential and Danish parents provide increasingly important feedback on how their child's disability affects daily living. The Nordic Five to Fifteen (FTF) parent questionnaire is widely used in Nordic countries to detect atypical or delayed development in children. Our study evaluated its internal validity and whether it could be used to generate a common disability variable across childhood neurological disorders and severities. METHODS: The 28-statement FTF questionnaire was completed by the parents of children with spina bifida, muscular disorders, spinal atrophy, cerebral palsy, blindness, deafness, mental retardation and disability, who received treatment for brain tumours. Psychometric analysis and Rasch analysis of the five FTF code qualifier level data were carried out. RESULTS: A total of 227 of 332 (68.4%) parents participated. The mean qualifier score was 3.06 (standard deviation 0.89, range 2.31-4.26), and the variances mean was 1.57 (range 0.87-2.38). The corrected code-total correlation was 0.65, and reliability was 0.96. The Rasch analysis demonstrated good fit alignment of codes. CONCLUSION: The FTF questionnaire can be used with children with neurological disabilities, and the Rasch scale analysis results indicate that it could form the analytical basis for developing a common disability variable.