Background: Laser-assisted hair removal has become popularized using wavelengths in both the red and infrared regions of the electromagnetic spectrum. These photoepilation devices target follicular melanin or an exogenous pigment placed within the follicle resulting in thermal damage to the hair follicle and shaft. However, melanocytes and keratinocytes located within the superficial layers of the skin also absorb red and infrared laser radiation. This may result in unwanted epidermal injury during the hair removal process. Objective: The purpose of this study was to examine a large patient population to determine the frequency of side effects using 3 different hair removal laser systems with various wavelengths, pulse durations, and treatment protocols. Methods: A retrospective chart review and digital photographic analysis of the side effects resulting from 900 consecutive laser-assisted hair removal treatments delivered over a 24-month study period, by means of either a Q-switched Nd:YAG laser with pretreatment wax-epilation and topical carbon solution, a long-pulse ruby laser with a contact cooling tip, or a long-pulse alexandrite laser are reported. Results: Treatment pain, erythema, edema, hypopigmentation and hyperpigmentation, blistering, crusting, erosions, purpura, and folliculitis were observed. The majority of undesirable tissue effects occurred on tanned skin or in Fitzpatrick skin phototypes III and higher. The ruby and alexandrite laser systems resulted in the majority of side effects seen. The effects of seasonal variations, anatomic treatment location, and sun exposure were striking within the ruby and alexandrite laser groups. No infections, scarring, or long-term complications occurred. Conclusion: Laser-assisted hair removal is a safe procedure when patient characteristics such as skin type, anatomic location, and sun-exposed or tanned skin are considered during selection of laser treatment parameters. Lasers emitting wavelengths with high melanin absorption capabilities should be used in a conservative manner when treating patients with dark skin phototypes or suntans. No long-term complications, infections, or scarring occurred in this study population. (J Am Acad Dermatol 1999;41:165-71.)