The Q-switched ruby and the Q-switched neodymium YAG lasers are both widely used in the treatment of amateur and professional tattoos. Comparative evaluation of these two laser systems has not previously been performed; thus, the advantages of each laser have not been delineated. Forty-eight amateur and professional tattoos were treated with both the Q-switched ruby and Q-switched Nd:YAG lasers. The tattoos were divided in half and one side of the tattoo was treated with each laser. After one treatment, the patients returned for evaluation to assess the degree of lightening achieved by each laser. The Q-switched ruby laser was found to be superior in lightening black dye in both professional and amateur tattoos. A significant advantage was noted for the ruby laser in the removal of green tattoo pigment. The differences with the Q-switched ruby laser and the 1064 nm option of the Q-switched YAG laser were not clinically significant in the lightening or removal of other colors. The 532 nm option of the Q-switched YAG laser was superior to the Q-switched ruby and the 1064 nm option of the YAG laser in the removal of red tattoo colors in professional tattoos. Hypopigmentation was found more commonly with the Q-switched ruby laser, while textural change was noted more commonly with the Q-switched Nd:YAG laser. One of the patients treated with the Nd:YAG laser at 1064 nm showed a hypertrophic scar.