Lower rates of smoking cessation and higher rates of lung cancer in African American (AA) smokers may be linked to their preference for mentholated cigarettes. This study assessed the relationship between menthol smoking, race/ethnicity and smoking cessation among a diverse cohort of 1688 patients attending a specialist smoking cessation service. 46% of the patients smoked mentholated cigarettes, but significantly more AA (81%) and Latino (66%) patients than Whites (32%) smoked menthols. AA and Latino menthol smokers smoked significantly fewer cigarettes per day (CPD) than non-menthol smokers (15.7 vs. 20.3, for AA, and 17.0 vs. 22.1, for Latinos), with no differences among White menthol and non-menthol smokers. At 4-week follow up, AA, Latino and White non-menthol smokers had similar quit rates (54%, 50% and 50% respectively). In contrast, among menthol smokers, AAs and Latinos had lower quit rates (30% and 23% respectively) compared with Whites (43%, p < 0.001). AA and Latino menthol smokers had significantly lower odds of quitting [odds ratio (OR) = 0.34; 95% CI = 0.17, 0.69 for AA, and OR = 0.32; 95% CI = 0.16, 0.62 for Latinos] than their non-menthol counterparts. At 6-month follow up, a similar trend was observed for the race/ethnicity subgroups, with AA menthol smokers having half the odds of being abstinent compared with AA non-menthol smokers (OR = 0.48; 95% CI = 0.25, 0.9). Despite smoking fewer CPD, AA and Latino menthol smokers experience reduced success in quitting as compared with non-menthol smokers within the same ethnic/racial groups.