This study assessed the effect of treating nicotine dependence in smokers undergoing inpatient treatment for other addictions. It was a prospective, nonrandomized, controlled trial with a 1-year outcome. The subjects were smoking patients (50 controls, 51 in intervention group) in an inpatient addictions treatment unit in a medical center. The enrollment of subjects was sequential: controls were enrolled first; after a 6-week washout period, intervention subjects were enrolled. Controls received usual care, and the intervention group received nicotine dependence treatment consisting of a consultation, 10 intervention sessions, and a structured relapse prevention program. Smoking cessation rate and abstinence from alcohol or other drug use were the main outcome measures. The confirmed smoking cessation rate at 1 year was 11.8% in the intervention group and 0.0% in the control group (p = 0.027). Nicotine dependence intervention did not seen to interfere with abstinence from alcohol or other drugs (1-year relapse rate was 31.4% in the intervention group and 34.0% in controls). In this study, nicotine dependence treatment provided as part of addictive disorders treatment enhanced smoking cessation and did not have a substantial adverse effect on abstinence from the nonnicotine drug of dependence.