Background: the use of low-power lasers (as opposed to high-power lasers that can destroy tissue by a photothermal effect) has steadily increased in diverse areas of medical practice that require healing, prevention of tissue death, pain relief, reduction of inflammation, and regenerative medicine. Nevertheless, this modality, which is variously known as LLLT or photobiomodulation, remains controversial. The reasons for this lack of general acceptance among both the medical community and the general public at large are 2-fold. First, widespread uncertainty and confusion exists about the mechanisms of action of LLLT at the molecular, cellular, and tissue levels. Many of the most compelling applications of LLLT are in the field of neurology (both central and peripheral). Many serious brain diseases and injuries can be successfully treated with noninvasive transcranial laser therapy. Furthermore, in the peripheral nervous system, LLLT can be used effectively for nerve regeneration and pain relief. Experimental studies that were conducted during World War II by Gutmann and Young indicated that the rate of outgrowth and axon numbers were not affected by delayed nerve repair. These findings, with evidence of extreme atrophy of the denervated muscles, led to the erroneous conclusion that poor functional recovery after nerve injury was due to irreversible denervation atrophy of muscle and its inability to accept innervation, especially after long periods of time. Recent studies showed that low-level laser therapy (LLLT) accelerates the regeneration process of injured peripheral nerve tissue.