A laser is a device that produces a parallel bundle of photons of equal wavelength that are temporally and spacially in phase. The laser light can be focused to produce high energy in very small spots. The pulsed dye laser, the argon laser and the carbon dioxide laser are commonly used in dermatology. The pulsed dye laser and the argon laser are especially effective for cutaneous vascular lesions such as port-wine hemangiomas. It is important for the physician to be knowledgeable about laser-tissue interaction and laser safety to avoid laser accidents.