As the number of runners has increased dramatically, so has the incidence of running-related injuries. In order to determine what training factors are associated with running-related injuries, as well as what percentage of injured runners seeks professional medical attention, a random sample of entrants to a 10 kilometer race was asked to complete a questionnaire. There were 451 respondents, 355 men and 96 women, with a nonresponse rate of 12.7%. Nonrespondents did not differ from respondents with regard to age or sex. Forty-seven percent of respondents indicated that they had sustained a running-related injury in the last 2 years. Injured runners differed significantly from noninjured runners in that they were more likely to have run more miles per week, run more days per week, run a faster pace, run more races in the last year, stretched before running, and not participated regularly in other sports. Associated with injury, but not statistically significant, were those who had run marathons and had done muscle-strengthening exercises. No association was found with regard to the length of time running, running surfaces, part of the foot first contacting the ground, or running intervals, sprints, or hills. Seventy percent of those injured sought professional medical care, with 76% of these having a good or excellent recovery from their injuries. Compliance with medical advice correlated well with treatment success.