We sought to evaluate the economic impact and diagnostic utility of magnetic resonance imaging (MRI) in the management of patients with headache and nonfocal physical examinations. Computerized medical records were retrospectively reviewed of 1,233 patients presenting for MRI of headache at our institution over a 3-year period (1992-1995). Patients with focal findings at physical examination, prior brain surgery, head trauma, or immunocompromise were excluded. A model was developed to assess the cost associated with the MR test results, and actual average institutional costs of performing an examination applied. Correlative statistical analysis of referring specialties and positive tests was also performed. Three hundred twenty-eight patients who met the above criteria were retained in the sample. One hundred sixty-three patients (50%) had negative MR test results. Of the 50% of patients with positive studies, only 5 (1.5%) had clinically significant MR results. The average cost of an MR examination was 517 dollars (1998 dollars). The cost per clinically significant managed case detected was 34,535 dollars. No statistically significant difference was found among referring specialties and clinically significant MR results. Our results indicate that MRI of nonfocal headache yields a low percentage of positive clinically significant results and has limited cost-effectiveness. Referring specialty had no significant bearing on these outcomes, regardless of specialist experience.