To assess whether Health Risk Appraisal (HRA), a computer-scored lifestyle analysis questionnaire, can result in significant changes in health behavior, a controlled clinical trial with one-year follow-up was conducted among entering freshmen at an urban state university. Three hundred fifty entering freshmen were each assigned to one of four groups: HRA with feedback, HRA without feedback, initial control, and final control. Twenty-two per cent of the nonsmokers in the no-feedback group, as compared with 5% in the feedback group, acquired the habit of cigarette smoking (p less than 0.001). Furthermore, 26% of the smokers in the feedback group, as compared with 6% in the no-feedback group, were able to quit smoking (p less than 0.05). Among those unable to quit smoking, 59% in the feedback group, as compared with 19% in the no-feedback group, were able to reduce their cigarette consumption by more than six cigarettes per day (p less than 0.01). Health Risk Appraisal, when accompanied by feedback counseling, was an effective health promotion tool to help prevent nonsmokers from acquiring the habit and to modify cigarette smoking behavior among college freshmen.