Background: Myofacialpain syndrome and fibromyalgia are two painful clinical disorders of soft tissues that encountered to pain specialists. Low level laser therapy is one of the nonpharmacological treatment modality seems controversial. Aim of this review articles is to investigate of the efficacy of low level laser therapy (LLLT) in fibromyalgia and myofacial pain patients inthe literature.Methods: A comprehensive evaluation of the literature relating to LLLT in fibromyalgia and myofacial pain syndrome patients was performed. 34 articles allocated for this study The time frame covered was 2000 to 2010. Not only the journals of laser therapy allocated for this study, but also varieties of journals of medicine specialties selected for avoidance of bias error.Results: From 34 articles, 13 articles supported, the efficacy of low level laser therapy in pain score, in12 studies there was no difference between (LLLT) and placebo and did not study for pain criteria in9 studies. In case of the number of trigger points, 2 studies supported, the efficacy of (LLLT), there was no difference between (LLLT) and placebo in 5 studies and did not study for number of trigger points in 9 studies. For patient's quality of life, (LLLT) significantly improved of this criteria in 10 studies, there was no difference between (LLLT) and placebo in7 studies and did not study for patient's quality of life in 7studies. The increased levels of 5-hydroxy-tryptamine, 5-hydroxy-tryptophan and 5-hydroxy indol acetic acid, reported in one sudy.Conclusion: This study revealed that, application of LLLT was effective in pain relief, improvement of functional ability and patient's quality of life and number of trigger points in 15 studies. However, no significant differences were obtained between placebo and LLLT in 6 studies. In conclusion, although the laser therapy has no superiority over placebo in few groups in this study, we cannot exclude the possibility of effectivity of LLLT in fibromyalgia and myofacialpian syndrome patients. We recommended another treatment regimen including different laser wavelengths and dosages (different intensity and density and/or treatment interval) for this aim.