Neurologic impairment and sacral spinal anomalies are a finding in children with imperforate anus. The neurologic deficits previously had been considered static rather than progressive. Recent experience at this institution has documented the frequent association of imperforate anus patients having bony sacral and other spinal deformities with progressive neurologic dysfunction. These deficits are related to underlying spinal cord anomalies, which may be amenable to neurosurgical correction. To investigate the nature and frequency of such lesions, spinal cord imaging was done in these patients. From July 1976 to June 1985, 106 patients with imperforate anus were screened with plain radiographs of the sacral spine; 37 (35%) patients had abnormalities. Of these, 26 have been evaluated with a variety of spinal cord imaging techniques, including magnetic resonance imaging (18), digital metrizamide myelotomography (14), computed tomography (10), metrizamide myelography (5), or ultrasound (4). Four patients were lost to follow-up, and seven have not yet been studied. Fifteen of the 26 patients (53%) had one or more abnormal studies. Thirteen were considered to have progressive dysfunction with operable lesions and have undergone neurosurgical correction. At follow-up, there was improved leg function in five patients and improved bladder function in two patients. No patient had additional neurologic deficits after surgery. Because of the high incidence of progressive but potentially correctable myelodysplasias in patients with coexisting anorectal and sacral anomalies, routine radiographic screening of the spine is recommended, followed by spinal cord imaging and neurosurgical evaluation if warranted.