Sixteen patients with cosmetic tattoos participated after being informed of the nature of the protocol and giving consent. The protocol was approved by the Subcommittee for Human Subjects of the Massachusetts General Hospital, Boston. Patients were enrolled on a consecutive basis as long as their tattoos were partly black and previously untreated. The restriction to black tattoos allowed for a reasonable chance for pigment lightening, given the response of black tattoos to 1064-nm radiation and the low fluences used in the study (vide supra), and easier correlation between clinical responses and in vitro black pigment alterations induced by laser. Of the 16 tattoos, 15 were created by a professional and 1 was done by an amateur. Eleven of the tattoos were multicolored, most of these containing black, red, and green pigments. The remaining 5 clinically showed only black pigmentation. Tattoos were divided into 3 parts, the first 2 parts being the treatment sites for comparison between pulse durations. These sites were designated either as the left or right symmetrical parts of a representative portion of the whole tattoo. Part 1 was treated with a mode-locked Q-switched neodymium:YAG laser (Model YG501, Quantel Technologies, Santa Clara, Calif) delivering 35-picosecond pulses. Spot size, fluence, and repetition rate were 1.4 mm, 0.65 J/cm2, and 10 Hz, respectively. The beam profile was gaussian. Part 2 was treated with a Q-switched neodymium:YAG laser (Model NY82-10, Continuum, Santa Clara, Calif). Laser parameters were identical to part 1 except for pulse duration, which was 10 nanoseconds, and the beam profile, which was multimodal. The remainder of the tattoo was treated with the same laser values as those for part 2 except with parameters conventionally used in clinical practice (fluence of 8.0 J/cm2 and 2.5-mm spot size). Both laser units used an articulated arm and focusing handpiece lens assembly for beam delivery. Care was taken to avoid gross overlapping of adjacent exposure sites. For all treatment sites, the patients underwent 4 treatments in the described manner at 3- to 4-week intervals. All pulse energies were verified with an energy meter (Model 365, Scientech, Boulder, Colo) prior to each treatment. The beam profiles and spot sizes were determined by imaging the beam with a charge-coupled device camera (Model TM-34KC, Pulnix, Sunnydale, Calif) as follows. A black surface was placed at the object distance in front of the articulated arm. The surface was brought into the focus of the camera so that the laser spot was in the field of view. The video signal was input into a frame grabber (CX100, Image Nation Corp, Beaverton, Ore) interfaced with a personal computer. After capturing the image, the beam size and profile were determined with the aid of imaging software (NIH Image, National Institutes of Health, Bethesda, Md).