Smoking causes chronic obstructive pulmonary disease (COPD), but few controlled studies have tested anti-smoking treatments in COPD. With procedures likely to attract unmotivated persons we recruited 49 quite-ill, smoking COPD patients. During one or two daily home visits for 85 days, breath carbon monoxide (CO) and self-reports of daily smoking were obtained. Patients, given quit dates and nicotine gum (2-mg pieces, up to 30 per day), were assigned randomly to three groups: Experimentals were reinforced with lottery tickets for CO < 10 ppm. Cigarette Self Report (CSR) patients were reinforced for reporting no smoking that day. Controls received non-contingent payments. Each group's mean CO level fell at the quit date. Thereafter, reinforced patients maintained significantly lower CO levels than Controls. Although many more 24-h abstentions occurred in the intervention period than in baseline, few patients sustained abstinence; the groups did not differ in that regard. Outcome was predicted by decisions to throw away cigarettes when intervention began, but not by motivation scales nor Fagerstrom dependence scores. Pay schedules apparently exaggerated self-reports of reduced smoking. Although results are statistically significant, there is still no proven, practical treatment for smoking in advanced COPD.