Background: Prior research suggests that racial/ethnic minority smokers experience more difficulty with cessation than white smokers and access formal treatment less often. Minority smokers may respond differently to treatment interventions than white smokers. This prospective, observational cohort study compared long-term cessation outcomes among four racial/ethnic groups after an aided quit attempt using nicotine replacement therapy (NRT). Methods: A random cohort of smokers (N=1782) who recently filled a prescription for NRT was selected, stratified by race, using Minnesota Health Care Programs (e.g., Medicaid) pharmacy claims databases between July 2005 and September 2006. The primary outcome was 7-day point prevalence abstinence, which was assessed about 8 months after the NRT index prescription fill date using a mixed-mode survey protocol. Results: The overall survey response was 58.2%. Overall, abstinence outcomes did not significantly vary by race. Unadjusted comparisons show that among survey respondents, at 8 months, 7-day point prevalence abstinence was 13.8% among whites, 13.6% among blacks, 14.1% among American Indians/Alaska Natives, and 20.7% among Asians (p=0.42). Similarly, the 30-day duration abstinence was 10.0% among whites, 11.5% among blacks, 8.9% among American Indians/Alaska Natives, and 18.3% among Asians (p=0.14). In multivariate analysis using propensity adjustment for potential confounding and response bias, there was no evidence that the effectiveness of NRT was lower for racial/ethnic minority smokers compared to white smokers. Conclusions: These findings indicate that racial/ethnic minorities are as likely to quit smoking at a level similar to whites when using cessation treatment that includes NRT. Given documented disparities in the use of evidence-based cessation treatments such as NRT, interventions are sorely needed to improve access and utilization of these treatments in racial/ethnic minority groups.