Effectiveness of the rear seat in protecting occupants of different age groups in frontal crashes for 2000-2009 model years (MY) of vehicles was estimated and compared to 1990-1999 model years of vehicles. The objective was to determine the effectiveness of the rear seat compared to the front seat for various age groups in newer model year vehicles. The double paired comparison method was used to estimate relative effectiveness. For belted adults of the 25-49 age group, the fatality reduction effectiveness of the rear seat compared to the right front seat was 25 % (CI 11% to 36%), in the 1990-1999 model year vehicles. The relative effectiveness was -31% (CI -63% to -5%) for the same population, in the 2000-2009 model year vehicles. For restrained children 0-8 years old, the relative effectiveness was 55% (CI 48% to 61%) when the vehicles were of the 1990-1999 period. The level of effectiveness for this age group was reduced to 25% (CI -4% to 46%) in the 2000-2009 MYs of vehicles. Results for other age groups of belted occupants have followed a similar trend. All belted adult occupants of 25+ years old were significantly less protected in rear seats as compared to right front seats in the 2000-2009 model years of vehicles. For unbelted occupants however, rear seats were still a safer position than front seats, even in the 2000-2009 model years of vehicles.