The treatment of cutaneous blood vessel disease processes has produced inconsistent results. Lesions such as portwine stains and telangiectasia have responded occasionally with resolution of the lesion but often do not respond or develop serious adverse side effects. The argon laser, which has made the greatest gains in treating these lesions, can still produce serious scarring, skin texture changes or adverse discoloration. The pulsed dye laser has reduced these risks but is unable to afford the patient optimal results with current design constraints, principally a short 360 use c pulse duration. Larger diameter and deep seated vessels will not resolve. A pulsed dye laser with millisecond range pluse duration capabilities will be developed and clinically evaluated for the cutanueous laser-tissue interaction in both normal and lesional skin. It is anticipated the longer pulse duration will allow better lesional resolution while maintaining minimal patient risk. Results from the Phase-I studies will direct future laser development toward opitimizing clinical outcome.