Since the late 1970s, occupant fatalities in U.S. large truck accidents have generally shifted from truck occupants to occupants of other vehicles (primarily autos and light trucks). This paper analyzes that shift by estimating a regression model of a death ratio (other vehicle occupant fatalities to truck occupant fatalities) using annual time-series data for the 1975-1999 period. The regression includes two ratio explanatory factors-car size to truck size, and nontruck vehicle miles to truck vehicle miles-and one non-ratio explanatory variable, the proportion of young drivers. The vehicle size ratio has a statistically significant negative relationship with the death ratio (i.e., an increase in the size ratio contributes to a shift from other vehicle occupant deaths to trucker deaths); and the vehicle miles ratio has a significant positive association with the fatality ratio (i.e., an increase in the vehicle miles ratio promotes a shift from trucker fatalities to other vehicle occupant fatalities). The proportion of young drivers has a significant negative relationship with the fatality ratio.