Abstract: Objective To evaluate the long-term effects and safety of diode laser in hair removal. Methods A retrospective study was conducted. In this study, 350 patients with hypertrichosis were treated by an 800-nm diode laser with a pulse duration of 30 ms for various sessions. Two groups were divided based on the treatment sessions: group A receiving 6 （≥4 for axillae） or more treatments, group B less than 6 （< 4 for axillae） treatments. Patients were followed up for 8 months to 3 years （mean 22.5 months） by return visit or telephone. Evaluation of efficacy and side effects were performed. Results Follow-up and evaluation were completed in 235 patients, and a total of 375 sites treated. After 2-18 treatments, a total effective rate of 80.53% （302/375） was achieved. Significant higher effective rates were observed in group B compared with group A at all sites 86.84% （33/38） vs 35.00% （7/20） on the lips, 68.42% （26/38） vs 30.77% （4/13） on the face and neck, 92.00% （46/50） vs 55.56% （5/9） in lower extremities, 86.96% （20/23） vs 50.00% （4/5） on the trunk, 93.81% （91/97） vs 55.56% （5/9） at the axillae, 92.16% （47/51） vs 73.68% （14/19） in the upper extremities （all P < 0.05). Side effects were noted in only 6 cases, including hyperpigmentation, itching, and development of follicular papules, blisters and white hair. Neither hypopigmentation nor scarring was observed. Conclusions Diode laser system is effective and safe for hair removal. The effect varies with lesional sites and treatment sessions.

Key words: Hair removal, Diode laser