To examine the hypothesis that the prophylactic use of clean intermittent catheterization can prevent urinary tract deterioration in infants and young children with myelomeningocele a prospective controlled study was performed on 24 patients. Preliminary results indicate that more than 50 per cent of the patients with bladder sphincter incoordination managed by self-voiding had urinary tract deterioration. In contrast, in only 10 per cent of the patients treated prophylactically with clean intermittent catheterization did deterioration occur. We conclude that when bladder sphincter incoordination is diagnosed in children with myelomeningocele they are at a high risk for the development of future urinary tract injury. The prophylactic use of clean intermittent catheterization can actually prevent this deterioration and its use in this manner is recommended.