Background  Treatment of medium-sized congenital melanocytic naevi (CMN) can be challenging.

Objectives  To present the results of treatment of 55 CMN with the carbon dioxide (CO2) and pigment-specific lasers.

Methods  CO2 and Q-switched lasers (frequency-doubled Nd:YAG, Nd:YAG and alexandrite) were used to treat 55 CMN. Patients were treated at 3-month intervals until maximum clearance. Clinical response at 3–6 months after final treatment was graded as poor (< 50%), good (50–75%) or excellent (> 75%). Outcomes were evaluated on case note review and questionnaire.

Results  Thirty-six of the 55 CMN were macular and 19 were mammillated. Twenty-seven CMN were present on the head and neck. For macular CMN, outcomes were better for truncal CMN. Scarring and pallor were seen in three lower limb macular CMN treated with a CO2 laser. Mammillated CMN on the head and neck showed most improvement. Pigment-specific lasers were of no additional benefit. Repigmentation occurred in 6% of macular and 21% of mammillated CMN. Partial or complete regimentation of CMN was reported by 46% of patients.

Conclusions  Compared with macular CMN, mammillated CMN show a marginally better response to laser treatment. CMN on the limbs respond poorly. Pigment-specific lasers do not lighten mammillated CMN. Adverse effects can occur with CO2 laser treatment of macular CMN on lower limbs.