OBJECTIVE The copper vapour laser (CVL) and the frequency doubled Nd:YAG laser (FDNYL) have been increasingly adopted as alternatives to the argon laser for treating vascular skin lesions. Automated scanning devices that permit the use of any of these lasers at 30-50 ms pulse widths are now widely used. The object of this study was to compare the CVL and FDNYL with the argon laser using pulse widths in the 30-50 ms range. METHODS Thirty-one adult patients with red-purple or purple portwine stains (PWS) were treated with a CVL at 578 nm, a FDNYL at 532 nm, and an argon laser at 488/514 nm. Test areas were performed using a Hexascan delivery system and an energy fluence just sufficient to produce immediate tissue change. Pulse widths were maintained constant for each patient (mean 40 msec). The mean fluences used were 13.1 J/cm2, 13.2 J/cm2, and 13.0 J/cm2, respectively. Assessments were made after 4 months using a clinical fading score and an index of light absorbence derived from reflectance spectrophotometry. RESULTS Fading scores were statistically significantly better with the CVL (score = 2.29) than the FDNYL (score = 1.83, P < 0.02) and the argon laser (score = 1.89, P < 0.003). The differences between the FDNYL and the argon laser were not significant. Although there was a trend toward lower light absorbence index with the CVL than the argon laser and FDNYL (scores = 177, 179 and 181, respectively), these differences were not statistically significant. CONCLUSIONS Despite slightly better results with the CVL in terms of the fading produced, differences among the CVL, FDNYL, and argon lasers are small when 30-50 ms pulse widths are employed and are of doubtful clinical significance for darker PWS.