Twenty-three children with acute transverse myelopathy (ATM) are reviewed. Antecedent minor trauma or exercise was reported in 10 patients. Despite a positive history in 7 patients no preceding infection was documented. Two patients had a history of less severe ATM followed by recovery prior to a second more severe episode. The most common initial symptom was back pain and the most prominent clinical signs were weakness, sensory level and sphincter disturbances. Myelography and CT myelography at presentation was performed to exclude a compressive lesion. Spinal cord enlargement was demonstrated in 6 of 21 cases. Magnetic resonance imaging (MRI) of the spinal cord, performed in one patient, showed enlargement of the cord. Poor prognostic features were severity of weakness at the time of maximum deficit and a delayed onset of recovery. Maximum motor recovery occurred at a mean of 6 1/2 months but did not occur in one patient until 1 1/2 years. Normal or good outcome was obtained in 64%.