Since the introduction of selective photothermolysis, Q-switched nanosecond lasers have been used for the treatment of dermal pigmented lesions. Over the past several years, picosecond lasers have been introduced to the cosmetic community. We recently performed a study comparing a 550 picosecond 755nm laser versus a 50ns 755nm laser, with the purpose of evaluating the clinical efficacy and complications of each laser when treating nevus of Ota. Ten Asian patients with nevus of Ota were enrolled in the study. Each lesion was split into 2 parts, and patients were treated with a 755nm picosecond laser (PSL) and a 755nm nanosecond laser (NSL). The clinical endpoint for fluence choice was immediate whitening (PSL: 2.33 ~ 3.36J/cm2, NSL: 5.5 ~ 7J/cm2) of the treated area. The pulse duration was fixed at 550 picoseconds (PSL) and 50ns (NSL). The spot size of each laser was 2.5-3mm. Laser treatments were performed until excellent clinical improvement was observed. Patients were examined 1week after the first treatment, at each follow-up visit, and 6months after the last laser treatment. The average number of treatment sessions to achieve excellent clinical improvement was 4.2 treatments using PSL and 5.4 treatments using NSL. One case of hyperpigmentation and one case of hypopigmentation were observed in the NSL treatment group. There were no complications in the PSL treatment group. The 755nm 550 picosecond laser is significantly more effective than the 755nm 50ns laser in the treatment of nevus of Ota. The PSL treatment group also had minimum side effects.