ObjectiveTo evaluate injury rates and patterns in off-road bicycle racing, and to compare the findings in male and female cyclists.SettingThe study was conducted from 1994–2001 at a large off-road bicycling competition held for 4 days each summer at Mammoth Mountain, California.DesignInjured cyclists were evaluated at the first aid station or at the local hospital. Registration data were used to estimate the number of male and female competitors in each race.ParticipantsCyclists who sustained an injury during a race and were unable to finish the race due to the injury were included in the study. 22 female subjects and 71 male subjects met the inclusion criteria during the 8-year study period. There were a total of 20,769 race participants during the study period.Main Outcome MeasuresInjuries were categorized, and injury rates were calculated.ResultsThe overall injury rate during the study period was 0.77% (22/2,869) for women versus 0.40% (71/17,900) for men (p = 0.01). Fractures were sustained by 45.5% (10/22) of female subjects versus 21.1% (15/71) of male subjects (p = 0.03). Odds ratios indicate that overall, women were 1.94 times more likely than men to sustain an injury and 4.17 times more likely to sustain a fracture.ConclusionsThese data suggest that although participation in this sport is higher among men, the risk of injury is greater for women.