The North Carolina General Assembly approved a law effective in October 1985 that mandated seat-belt use by front-seat occupants of passenger vehicles. In January 1987, a $25 fine for infractions of this law went into effect. This study examined numbers of car occupants with severe and fatal injuries in crashes in North Carolina, controlling for the amount of vehicle damage as a measure of crash severity. After the law, significant decreasing trends were seen in the percentages of front-seat occupants who had severe or fatal injuries in crashes, although the involvement of alcohol in crashes was still associated with an increased risk of such injury. Projections indicate that a reduction of approximately 1100 severe or fatal injuries per year can be attributed to the seat-belt law in North Carolina. This study supports the hypothesis that the societal burden of crash-associated injury can be reduced by mandating seat-belt use.