Wine colored nevi (PWSs) are the most common vascular malformation at birth. the most prominent treatment for PWSs is laser therapy, typically the pulsed dye laser (PDL). pDL treatment is based on the theory of selective photothermolysis, in which oxyhemoglobin selectively absorbs radiant light resulting in the destruction of swollen blood vessels. During PDL irradiation, it is useful to depict the edges of the PWS while properly treating the entire lesion. The exact edges of the lesion are difficult to see when the physician wears protective laser glasses during treatment. In addition, there is often reactive vasodilation during laser treatment manipulation, which can make the edges of the lesion blurred. Finally, many ink pens increase the risk of laser protection because pigments may also absorb laser energy. There have been reports of sparks burning the skin when the laser beam comes in contact with pigmented ink. Initially, we use a yellow highlighter to define the edge of the lesion, but it is difficult to remove. We describe a technique to safely mark the edges of PWSs using a white gel pen during PDL treatment. Technique The clinical edge of the lesion is marked with a white gel pen (The Ultimate Gel Pen, Pastel by American Crafts, Japan) prior to application of anesthetic as well as laser irradiation. If the edges of the lesion have faded after previous treatment, photographs of the previous lesion can be used to determine the edges of the lesion. The white gel pencil line remains unaffected during PDL treatment. The risk of superficial skin damage due to ink absorption of the laser is eliminated. After treatment is complete, the white pen markings can be easily removed using a wet cotton swab.