Principles of biostimulation via therapeutic lasers was introduced more than 20 years ago when they were used in dermatology for wound healing. According to Genovese, biological effects caused by low level lasers are due to low energy deposited into tissues where deposited energy results in primary, secondary and general therapeutic effects. This results in the analgesic and anti-inflammatory effects as well as in improvement in healing. LLLT acts according to the Arndt-Schulz principle which states that if the stimulus is too weak, no effect is seen. Increased stimulation and optimal dose leads to the optimal effect ; while, further dose increase leads to a decreased effect. Additional stimulation leads to the inhibition of stimulation. It seems that LLLT act analgesically since they improve endorphin release and therefore inhibit nociceptive signals and control pain mediators. They can also act analgesically by inhibiting pain signals which partially leads to the transient varicosities along the neurons which decrease impulse transmission.