Background: As genetic testing for health risk becomes increasingly available, it becomes important to study the prospective impact of testing on modifiable health behavior. Purpose: This study examines the impact of genetic testing for alpha-1 antitrypsin (AAT) deficiency, a condition that usually results in emphysema in individuals exposed to cigarette smoke. We evaluated whether AAT testing, performed in the home and with minimal contact (reading materials including advice on cessation), results in quit attempts and abstinence. Methods: Identified smokers (N = 199) from a larger study of genetic testing were surveyed 3 months following receipt of their AAT genotype. The primary endpoint was the incidence of quit attempts. Results: Smokers who tested severely AAT deficient were significantly more likely to report a 24-hr quit attempt (59%) than were those who tested normal (26%). Carriers had a 34% quit attempt rate. Severely AAT deficient smokers were more likely than both carriers and normals to seek information on treatment, use pharmacotherapy for smoking cessation, and report greater reductions in their smoking. There were no group differences in 3-month abstinence rates. Conclusions: Knowledge of severe AAT deficiency, but not carrier status, may motivate smokers toward cessation. The AAT testing experience may have consequences for outcomes of other genetic conditions with modifiable health behaviors. © 2007 by The Society of Behavioral Medicine.