Smoking cessation can reduce both morbidity and mortality among patients who have heart disease. China has the largest number of smokers in the world, and most smokers have low motivation to quit. Regular smoking cessation services are almost nonexistent in China, and little is known about the psychometric properties of instruments in assessing smoking self-efficacy in Chinese, whose cultures differ greatly from those of Westerners. The present study tested the psychometric properties of the Chinese version of the Smoking Self-Efficacy Questionnaire (SEQ-12) among 1,841 Chinese smokers who had heart disease, including (a) factorial structure using confirmatory factor analysis, (b) reliability with Cronbach's alpha, (c) concurrent validity, and (d) predictive validity of successful quitting. Confirmatory factor analysis of the SEQ-12 revealed a modified two-factor model that provided a good fit to the data; item 6 ("urge to smoke") was an indicator for the external stimuli subscale rather than for the internal stimuli subscale. Internal consistency coefficients (.77 for external stimuli and .88 for internal stimuli) were acceptable. Baseline self-efficacy scores were significantly associated positively with stage of readiness to quit, and negatively with cigarettes smoked per day and Fagerstrom Test for Nicotine Dependence (FTND) score. Multivariate logistic regression analysis showed that successful quitting at 1 month and at 3 months were predicted by higher external stimuli score, fewer cigarettes smoked per day, lower FTND scores, and being in the intervention group. We concluded that the Chinese version of the SEQ-12 is a valid and reliable instrument for Chinese cardiac patients who smoke. The SEQ-12 can be used to assess smokers' self-efficacy so that appropriate smoking cessation interventions can be provided.