A consecutive series of 37 individuals admitted to the hospital for elective temporomandibular joint (TMJ) reconstructive surgery and 3 seen as outpatients with TMJ disease were evaluated for rheumatic disease or for another etiologic factor that might account for this problem. These 40 patients were screened by history, physical examination, and laboratory study. We soon noticed that many patients had generalized joint laxity. Eighteen of the first 40 individuals satisfied established criteria for the hypermobile joint syndrome. An additional 3 were found to have Ehlers-Danlos syndrome or a forme fruste of this disorder. Many were markedly hypermobile and could perform a number of flexible maneuvers. Although excessive joint laxity is known to be associated with a variety of rheumatic conditions, TMJ disease has not been recognized as one of them. No patient in this series had a systemic inflammatory disorder or any other apparent etiologic factor for TMJ disease. We suggest that there is a cause-and-effect relationship between generalized joint laxity and TMJ disease.