The aims of this study were (1) to determine the rate of 'idiopathic' scoliosis associated with neuroanatomical abnormalities of the posterior cerebral fossa (PCF), spinal canal (SC) or central nervous system (CNS), and (2) to identify any clinical, neuro-orthopedic criteria, radiological curve pattern or other variable which could justify magnetic resonance imaging (MRI) as complementary study. Fifty-six patients with juvenile and adolescent scoliosis, were prospectively evaluated with MRI of the PCF and SC. All the patients were categorized into four different groups according to neuro-anatomical abnormalities on MRI (groups A, B, C and D). Eleven patients (19.6%) presented neuroanatomical abnormalities of the PCF and SC (group A), four patients (7.1%) presented pathological conditions of the CNS (group B) and three patients (5.4%) presented anomalies at the osseous spine and abdomen (group C). The remaining 38 patients (67.9%) presented with normal MRI results (group D). Of the patients in group A, 81.8% were neurologically normal. In this group, the right and left thoracic curve patterns were seen in the same number of patients (four of 11 each). Early diagnosis of neuroanatomical abnormalities of the PCF, SC and CNS could be achieved in 26.7% of cases (groups A and B). The most significant finding was the chronological age: 36.4% of patients in group A were under the age of 11 years. In addition, it would be recommended that in patients with scoliosis and a surgical indication, MRI results should be to take into consideration as a complementary preoperative evaluation because four of 15 patients (26.7%) with an indication for spinal fusion and who were neurologically normal, sustained some of the conditions included in groups A and B.