Recently, many people are using insoles. They are used for structural and positional imbalance such as foot deformities. However, evidence of their effect remains unclear. The aim of this review is to investigate the scientific evidence on the effect of various insoles. A comprehensive review of the English-language scientific literature was carried out covering the period from April 1980 to January 2013 of MEDLINE, CINAHL and EMBASE databases, to search for articles relating to insoles for the prevention and treatment of lower extremity injuries. When data were available for stratification, we extracted information concerning patients with knee osteoarthritis (15 studies), Diabetes mellitus (3 studies) and other diseases (12 studies), comparisons of different insoles (10 studies), and sports injuries (6 studies). An improvement effect on alignment was found in femorotibial alignment; and it was suggested that such alignment is effective for knee osteoarthritis (OA). The insole has an effect on preventing the progression of the transformation of the foot part of patients with diabetes; and, as a result, it is thought of as an effective therapy for patients with diabetes. This review provides evidence for the beneficial effect of insoles in the treatment of some musculoskeletal disorders. However, some trials were compromised by poor methodology. Likewise, it is necessary to determine the effect of shoes, in addition to insoles, and to investigate their effect in the future.