INTRODUCTION: Cigarette smoking prevalence is more than two times greater among incarcerated adults, a population usually excluded from national health surveys. African American young adult (18-25) men are less likely to smoke cigarettes than their white counterparts. However, they are two and a-half-times more likely to be incarcerated. This study estimated smoking prevalence with noninstitutionalized and incarcerated samples combined to determine if excluding incarcerated adults impacts smoking prevalence for certain populations. METHODS: The Bureau of Justice Statistics last fielded the Survey of Inmates in State and Federal Correction Facilities in 2003-2004. We combined data from Survey of Inmates in State and Federal Correction Facilities (n = 17 910) and the 2003 and 2004 National Health Interview Survey (n = 61 470) to calculate combined cigarette smoking estimates by race/ethnicity, sex, and age. RESULTS: Inmates represented the greatest proportion of smokers among African American men. Among African American young adult men, inmates represented 15.2% of all smokers in the combined population, compared to 2.0% among white young adult men. Cigarette smoking prevalence was 17.6% in the noninstitutionalized population of young adult African American men and 19.7% in the combined population. Among white young adult men, cigarette smoking prevalence was 29.8% in the noninstitutionalized population, and 30.2% in the combined population. There was little difference in estimates among women. CONCLUSIONS: The exclusion of incarcerated African American young adult men may result in a small underestimation of cigarette smoking prevalence in this population. Increasing access to smoking cessation support among inmates may reduce smoking prevalence in disproportionately incarcerated segments of the US population. IMPLICATIONS: The exclusion of incarcerated adults from national survey data should be considered when examining differences in cigarette smoking prevalence estimates between African American and white young adult men. Approximately one in six African American young adult men who smoke were incarcerated. Increasing access to smoking cessation support among inmates may reduce smoking prevalence among disproportionately incarcerated segments of the population.