Life expectancies were estimated for selected groups of smokers, ex-smokers, and nonsmokers based on the results of a 16-year mortality follow-up of 198,820 U.S. veterans. Life expectancy varied inversely with number of cigarettes smoked per day. The most pronounced differences were between nonsmokers and heavy cigarette smokers (40+ per day). These differences in life expectancy were greatest at the younger ages--nearly 9 years at ages 35 and 40. Life expectancies for cigarette smokers varied directly with age began smoking. For all ages, differences in life expectancy between nonsmokers and ex-cigarette smokers who stopped for other than doctor's orders were less than those between nonsmokers and current cigarette smokers. Results in the present study clearly confirmed Hammond's earlier findings.