Prior studies have found a 3%-6% clinically significant error rate in radiology practice. We set out to assess discrepancy rates between subspecialty-trained university-based neuroradiologists. Over 17 months, university neuroradiologists randomly reviewed 1000 studies and reports of previously read examinations of patients in whom follow-up studies were read. The discrepancies between the original and "second opinion" reports were scored according to a 5-point scale: 1, no change; 2, clinically insignificant detection discrepancy; 3, clinically insignificant interpretation discrepancy; 4, clinically significant detection discrepancy; and 5, clinically significant interpretation discrepancy. Of the 1000 studies, 876 (87.6%) showed agreements with the original report. The neuroradiology division had a 2.0% (20/1000; 95% CI, 1.1%-2.9%) rate of clinically significant discrepancies involving 8 CTs and 12 MR images. Discrepancies were classified as vascular (n = 7), neoplastic (n = 9), congenital (n = 2), and artifacts (n = 2). Individual neuroradiologist's scores ranged from 0% to 7.7% ± 2.3% (n = 18). Both CT and MR imaging studies had a discrepancy rate of 2.0%. Our quality assessment study could serve as initial data before intervention as part of a PQI project.