The effect of the normal-mode ruby laser (NMRL) and the combined (normal mode plus Q-switched) ruby laser on congenital melanocytic nevi (CMN) was evaluated, and the degree to which both laser treatment regimens remove melanocytes was compared in 15 patients. Each nevus was marked to designate half of the lesion for the NMRL treatment and half of the lesion for combined ruby laser treatment. The efficacy of each laser treatment was correlated with the degree of clinical improvement determined by photographic assessment, histological examination, and melanin reflectance spectrometry before and 3 months after laser treatment. A single treatment using the NMRL with energy fluences of both 20 J per square centimeter and 30 J per square centimeter resulted in a slight, but not significant, improvement in lightening of pigmentation (42.61% and 30.38%, respectively). A better clinical response (excellent to good) and higher percentage of lightening (64.45%-72.43%) was noted in the combined ruby laser-treated areas than the NMRL-treated areas. Histological results showed that the combined ruby laser provided a marked decrease in the number of the nevomelano-cytic nests in both the junctional area and the papillary and reticular dermis, whereas the NMRL (with energy fluences of either 20 J per square centimeter or 30 J per square centimeter) caused a decrease in the junctional area and the papillary dermis. None of the nevi had complete clearance of the pigmentation after a single treatment. Therefore, multiple (four to five) treatment sessions are needed to cause complete removal of nevomelanocytic nests in CMN. In conclusion, the combined ruby laser is more effective than the NMRL alone in the treatment of CMN without scarring or textural change of the skin.