Objectives-To test the hypothesis that joint hypermobility may play a part in the pathogenesis of pain in fibromyalgia, schoolchildren were examined for the coexistence of joint hypermobility and fibromyalgia. Methods-The study group consisted of 338 children (179 boys, 159 girls; mean age 11*5 years, range 9-15 years) from one public school in Beer-Sheva, Israel. In the assessment of joint hypermobility, the criteria devised by Carter and Bird were used. Any child who met at least three of five criteria was considered to have joint hypermobility. Children were considered to have fibromyalgia if they fulfilled the 1990 American College of Rheumatology criteria for the diagnosis of fibromyalgia, namely, widespread pain in combination with tenderness of 11 or more of the 18 specific tender point sites. The blind assessments of joint hypermobility (by AG) and fibromyalgia (by DB) were carried out independently. Results-Of the 338 children 43 (13%) were found to have joint hypermobility and 21 (6%) fibromyalgia; 17 (81%) of the 21 with fibromyalgia had joint hypermobility and 17 (40%) of the 43 with joint hypermobility had fibromyalgia. Using x2 statistical analysis, joint hypermobility and fibromyalgia were found to be highly associated. Conclusions-This study suggests that there is a strong association between joint hypermobility and fibromyalgia in schoolchildren. It is possible that joint hypermobility may play a part in the pathogenesis of pain in fibromyalgia. More studies are needed to establish the clinical significance of this observation.