The role of MRA in the evaluation of children is evolving. We compared MRA and MRI in children with a variety of neurologic conditions to determine when MRA provides positive, cost-beneficial information. A total of 114 patients were retrospectively studied. MRA and MRI were performed and compared. MRA was abnormal in 34 (30%) of 114 patients: five (83%) of six with Menkes' disease, four (33%) of 12 with sickle cell disease, 12 (38%) of 32 with vascular malformations, one (6%) of 17 with headaches, seven (24%) of 24 with new focal deficits, one (10%) of 10 with seizures, and four (31%) of 13 with miscellaneous diagnoses. MRA and MRI were concordant in 73 (64%) of 114. Maximum concordance was in patients with Menkes' disease (100%) and minimum in those with new focal deficits (50%). The best MRA cost/benefit ratios were obtained in patients with Menkes' disease, vascular malformations, and sickle cell disease. A normal MRI usually forecasted a normal MRA. However, abnormal MRI findings did not always predict MRA abnormalities. Positive, cost-beneficial information is provided by MRA mostly in conditions known to involve the cerebral vasculature. Indications to perform MRA should be based on the neurologic diagnosis and MRI findings.