Analyses of motor vehicle fatality counts in New York and several comparison states for the years 1980 through 1985 indicate that New York's seat belt use law reduced fatalities by about nine percent during the first nine months of the law. This estimate is preliminary, and the estimated long-term effect of the law could change as more sophisticated analyses are applied to the data and as belt use changes (it had declined to less than 50 percent over most of the state by the end of the first year of the law). In addition, New York's law is one of the strongest in terms of enforceability, and the effect may be smaller in states with weaker laws. However, the estimated effect in New York is consistent with the experience of other countries with seat belt use laws.