Smoking rates among persons being treated with methadone for opiate dependence are exceptionally high. Nevertheless, there is debate about whether smoking cessation has a negative effect on substance abuse treatment outcomes. To understand patient perceptions of the interaction between smoking and illicit drug use, we administered the Nicotine and Other Substances Interaction Expectancies questionnaire (NOSIE) to 168 smokers-79% Caucasian and 48% female-at two methadone programs in Providence, Rhode Island. The four summed-rating scales of this 20-item instrument exhibited good to excellent internal-consistency reliabilities. The scales measured the effect of drug use on smoking (5 items, alpha =.84), the effect of smoking on drug use (3 items, alpha =.73), smoking to cope with drug urges (9 items, alpha =.91), and the difficulty of concomitantly quitting smoking and drugs (3 items, alpha =.72).Most subjects believed drug use increased smoking, but that smoking did not trigger drug use. Relatively few reported smoking to cope with drug urges and most did not consider quitting smoking and quitting drug use to be incompatible goals. NOSIE was a reliable instrument that offers insight into patient expectations of the interaction of smoking and drug use.