The aim of this study was to determine the prevalence of self- reported versus diagnosed stress fractures in female elite athletes and non-athletic controls. A random sample of Norwegian elite athletes from the national teams, aged 13-39 years (n = 186) and a random sample of non-athletic controls (n = 145) in the same age group participated in the study. The athletes represented a junior- or senior team, or a recruiting squad for one of these teams, in one of 46 different sports/events. A higher percentage of athletes self-reported stress fractures (14.0%) compared to those diagnosed with stress fractures (8.1%) (p < 0.001). Six controls self- reported stress fractures, but none of them were diagnosed with stress fractures. These results indicate that self-reporting of stress fractures has low validity. This finding has important implications for further research on stress fractures in athletes.

• This study is the first to compare self-reported and diagnosed stress fractures in the total population of elite athletes representing all kinds of sports.

• The results indicate that self-reporting of stress fractures has low validity in both athletes and non-athletic controls, and other measurement methods should be considered when evaluating possible stress fractures.

• Based on our results, stress fractures seem to be a sport-related injury.