Cognitive behavioral stress management (CBSM) has previously been found to reduce fatigue, depression, and cortisol response to heavy exercise training among competitive collegiate athletes and to speed physical and psychological recovery from surgery. Our study assessed the efficacy of a CBSM program to reduce the frequency of injury and illness among collegiate athletes in a randomized, single-blind, controlled clinical trial. Following assessment of baseline medical history, mood state, stress, cortisol, sleep, alcohol use, and exercise training, collegiate rowers were stratified by gender and competitive level and randomly assigned to either a control group or a CBSM group. Exercise training information and psychosocial assessments were repeated immediately following the intervention period, and health care providers who were blinded to participant assignment recorded the frequency of medical visits and the number of days injured or ill until the end of the season. Athletes randomly assigned to a CBSM group experienced significant reductions in the number of illness and injury days as compared to control group athletes. CBSM participants also had half the number of health service visits as did controls. The data suggest that a time-limited CBSM intervention designed specifically for an athlete population may be an effective prophylactic treatment to reduce the incidence of injury and illness among competitive collegiate athletes.