A 805-nm diode laser ablation therapy with indocyanine green (ICG) was studied for the endoscopic treatment of early gastric cancer. The ICG solution with 1mg/ml was administrated to the submucosa of the resected porcine and anesthetized canine stomach for the purpose of enhancing the tissue absorption to the laser light. We established complete removal of the mucosa and the submucosa with laser power of 12 or 25 watts. The proper muscle was intact because the ICG solution prevents the laser light penetration to the proper muscle. An ablated depth could be easily recognized by observing the ablated surface color. Our results showed that the combination of the 805 nm diode laser irradiation and the submucosal injection of the ICG solution might provide selective and controllable endoscopic treatment for early gastric cancer.