This study investigated the relationship of birth order to three conditions in which the severity of sustained injury tends to increase: (a) individual contact sports, (b) team contact sports, and (c) individual noncontact sports. Operating on the assumption that each of these conditions generated progressively greater degrees of fear regarding personal injury or death, the following hypotheses were advanced: (a) firstborn males are likely to indicate a lower preference for all three conditions of dangerous sports than later-born males, and (b) as each condition becomes progressively more dangerous, there is a correspondingly greater difference between firstborn and later-born preference. The subjects of the study were 67 firstborn and 99 later-born male college students. They were compared on their preference for participation in such sports as judo, football, lacrosse, sky diving, ski jumping, and motorcycle racing, among others. The results indicated that in general, firstborns were more likely to avoid dangerous sports than later-borns. The greatest discrimination was found in those sports in which the severity of physical injury is perceived to be high and the opportunity to attain a measure of security and peer support under stress is perceived to be low. (A list of references is included.) (Author/JS)