Naltrexone (NTX), by its pharmacological action in the mesolimbic pathways, should decrease reinforcement from nicotine as well as from alcohol. By means of this mechanism, NTX could result in temporary increases in smoking followed by decreased smoking rates among alcoholics not motivated to quit smoking. The change from pretreatment in smoking rates of 73 recently abstinent alcoholics in a 12-week clinical trial of NTX vs. placebo during alcoholism treatment was compared during 8 of the 12 weeks. Only smokers compliant with NTX were included in the analyses. NTX was associated with decreased smoking at every time point, but the effect was significant at only one time point. When alcohol relapsers were excluded, NTX patients showed decreased smoking at every time point, but the effect was significant at only two time points, a reduction of about five cigarettes per day. When smoking stage of change was included in the analyses, NTX showed no significant main or interaction effects on smoking rate. Precontemplators showed significantly less change in smoking rate than all other patients at the first and last four time points. Therefore, NTX alone currently does not show promise for promoting smoking reduction among recently abstinent alcoholics who have not sought or been given smoking cessation treatment. Further research is needed on possible effects with smokers motivated to quit smoking and on other methods of promoting smoking cessation among alcoholics.