We sought to identify and correct inaccurate perceptions of risk among 1,317 adult patients in a primary care setting. Patients' perceived risks of heart attack, stroke, cancer, and motor vehicle crash were assessed and compared with a measure of risk derived from a health risk appraisal. Patients were then randomly assigned to receive computer-generated individualized risk feedback, risk feedback plus behavioral change feedback, or no feedback. Changes in perceived risk from baseline to a 6-month follow-up were compared across study groups. Results showed that individualized risk feedback was effective in increasing perceived stroke risk among patients who had underestimated their stroke risk at baseline and in reducing perceived risk of cancer among patients who had overestimated their cancer risk at baseline. Individualized risk feedback did not alter patients' perception of their heart attack and motor vehicle crash risks.