Factors associated with quitting smoking were examined in 3,778 male and 1,486 female ever-smoking patients hospitalized with non-tobacco-related conditions interviewed between 1977 and 1985. Quitters were defined as those who had stopped smoking at least one year prior to admission. More than 80 per cent of male and female quitters had stopped more than five years prior to diagnosis. The lifetime quit rate (no. ex-smokers/no. ever smokers) X 100 was higher in males than in females, and in both sexes the quit rate increased with increasing age, education level, and occupational level. Jews had higher quit rates compared to non-Jews, and Whites had higher quit rates than Blacks. Those who were divorced or separated had lower quit rates than those who were not. In both sexes, light smokers and heavy smokers had elevated quit rates. The quit rate also increased with increasing interval between waking and smoking the first cigarette of the day. Logistic regression models were used to adjust simultaneously for the role of different variables.