Numerous reports have documented a lower prevalence of seat belt use among blacks in the United States, compared with whites. Limited data suggest that black-white disparities in states with primary seat belt laws (motorists can be stopped and cited solely for violating a seat belt law) are less marked than in states with secondary laws (motorists can be cited for violating a seat belt law only if stopped for another offense).Data from the Fatality Analysis Reporting System were analyzed in 2005 to compare seat belt use among 11,574 blacks and 73,639 whites aged 16 or more years killed in crashes from 1999 to 2003 in 33 states with a primary or secondary adult seat belt law and annual reporting of race for 80% or more of decedents. After stratification of states by type of seat belt law, logistic regression was used to calculate odds ratios and 95% confidence intervals (CIs) for seat belt use among blacks, relative to whites, with adjustment for age, gender, seat position, urban/rural region, and income.Odds ratios and 95% CIs for seat belt use among blacks were 1.05 (0.97-1.13) and 0.89 (0.83-0.95), in primary- and secondary-law states, respectively.Black-white disparities in seat belt use were mitigated in states with primary seat belt laws. Only 24 states have primary laws. Enacting primary laws in other states might reduce or eliminate racial disparities in seat belt use.