Objective: The goal ofthis study was to determine a relationship between light dose and the delay time between administration of Verteporfin and light to ablate canine esophageal mucosa. Materials and Methods: Verteporfin was administered IV (0.75 mg/lg). 630-nm light from KTP/Dye laser was delivered using a 9-cm diffuser inside a specially designed reflective 7-cm windowed balloon. Initially, animals were treated at doses of 160 J/cm, 180 J/cm, 200 J/cm, and 220 J/cm 2-3 hours after Verteporfin injection. Based on the acute response in these animals and the plasma Verteporfin clearance, other treatments were devised and tested at 60 J/cm (at 1 5 minutes), 80 J/cm (22 minutes), 100 J/cm (30 minutes), and 145 J/cm (60 minutes). Results: In initial animals, 200 J/cm at 2 hours induced acceptable mucosal ablation. Using this light dose and the plasma drug clearance, subsequent treatments were tested resulting in similar injuries using 60 3/cm (15 minutes), 80 3/cm (22 minutes), 100 3/cm (30 minutes), and 145 J/cm (60 minutes). Conclusions: A relationship was established relating the light dose and the delay time between administration oflight and Verteporfin for ablation ofnormal canine esophageal mucosa.