The etiology of idiopathic scoliosis is still unsolved, despite extensive research. This paper analyzes the different factors of relevance. Recent investigations have convincingly demonstrated the hereditary traits of idiopathic scoliosis. In the adolescent group a specific growth pattern has also been demonstrated, while muscular factors and biochemical changes of connective tissues are somewhat more uncertain. A significant number of patients demonstrate asymmetries in the vestibular apparatus and electroencephalographic abnormalities. Because of the essential role of the vestibular and central nervous systems in the postural equilibrium, functional asymmetries or minor pathologic changes in these structures might also be factors of importance. It is our view that adolescent idiopathic scoliosis should be regarded as a multifactorial disease. Combining the findings in recent investigations, a possible model for the pathogenesis of the disease is outlined.