We describe five cases of radiographically proven stress fracture of the pubic ramus in serious runners, three of whom were elite female marathoners. In a further two cases in which radiography failed to support the clinical diagnosis, there was bone scintigraphic evidence of stress fracture. Another five cases had the identical clinical presentation, but the diagnosis was not confirmed radiologically and bone scanning was not performed. Most patients experienced persistent groin discomfort during any activity for the first 4 weeks after injury, but all recovered completely after 8 to 12 weeks of rest, in particular, avoidance of running. In common with other studies, we found that the injury occurred in competitive runners, especially females, and was likely to develop during competitive races or intensive training sessions. We suggest that a diagnosis of pelvic stress fracture or stress fracture syndrome can be made with confidence, even in the absence of radiographic evidence, if the following three features are present in a long distance runner presenting with groin pain: First, activity causes such severe discomfort in the groin that running is impossible. Second, the athlete develops discomfort in the groin when standing unsupported on the leg corresponding to the injured side (positive standing test). In some cases the pain is so severe that standing on one leg is impossible. Third, deep palpation reveals extreme, exquisite nauseating tenderness localized to the pubic ramus and not to the overlying soft tissues. The diagnosis can be confirmed by bone scintigraphy where such facilities exist.