Objective Based on the assumption that children with spinal dysraphism are exposed to a large amount of ionising radiation for diagnostic purposes, our objective was to estimate this exposure, expressed in cumulative effective dose. Design Retrospective cohort study. Settings The Netherlands. Patients 135 patients with spinal dysraphism and under 18 years of age treated at our institution between 1991 and 2010. Results A total of 5874 radiological procedures were assessed of which 2916 (49.6%) involved ionising radiation. Mean cumulative effective dose of a child with spinal dysraphism during childhood was 23 mSv, while the individual cumulative effective dose ranged from 0.1 to 103 mSv. Although direct radiography accounted for 81.7% of examinations, the largest contributors to the cumulative effective dose were fluoroscopic examinations (40.4% of total cumulative effective dose). Conclusions Exposure to ionising radiation and associated cancer risk were lower than expected. Nevertheless, the use of ionising radiation should always be justified and the medical benefits should outweigh the risk of health detriment, especially in children.