Stabilization splint is the treatment of choice for pain control in temporomandibular disorder (TMD) patients, even though its mechanism of action is still unknown. The aim of this systematic review is to provide a critical overview of the effectiveness of stabilization splint therapy on the basis of currently available literature data. The available Medline database was searched and 24 studies published since the 1995s have been consequently included in this review. The selection criteria were randomized controlled trials and clinical trials comparing splint therapy to either no treatment or another active treatment (physiotherapy, relaxation and drugs). Studies were grouped according to treatment type. Based on the currently best evidence available, it appears that stabilization splint has similar efficacy in controlling TMD symptoms as other active treatments (physiotherapy, relaxation and drugs). Stabilization splint therapy may be beneficial in reducing pain at rest and on palpation when compared with non-occluding splint. During a short period, education was slightly more effective than occlusal splint in treating spontaneous muscle pain. These two treatments did not have significantly different effects on pain-free mouth opening and pain during chewing. This review has shown evidence that most TMD patients are helped by incorporation of a stabilization splint. There is not enough data on the long-term efficacy and effectiveness of this widely used therapeutic tool. In the future, there is a need for well-conducted randomized controlled trials paying attention to adequate sample size, blind outcome assessment, duration of follow up, and using standardized methods for measuring treatment outcomes.