Whether age or gender or both influenced severity of injuries suffered in head-on automobile collisions on rural highways was assessed. The initial hypothesis was that, because of physiological changes, and possibly other changes related to aging (including loss of bone density), older drivers and passengers would suffer more severe injuries when involved in head-on collisions. Results of logistic regression analysis indicate that four separate factors, incorporating 14 individual and interactive variables, were strongly related to injury severity. Individual variables included age of driver or passenger (either linear or quadratic), position in the vehicle, and form of protection used, along with a set of interactive variables (such as age and position). The importance of age-related effects in injury severity is verified by hierarchical and principal components logistic regression models, amplifying findings of exploratory stepwise logistic analysis. Variations in findings resulted when the population was divided by gender. Although age remained a very important factor in predicting injury severity for both men and women, use of lap and shoulder restraints appeared to be more beneficial for men than for women, while deployed air bags seemed more beneficial for women than for men.