The patient had no complains, blood stool test was positive. Colonoscopy revealed a laterally spreading tumor granular-type, NICE type 2, KudoIIIL, measuring 3,5x3,0 sm. Biopsy showed an adenoma HGD. Underwater conditions were required for the laser ESD. Tumor lifting was satisfactory. 1940-nm thulium laser with 940-μm fiber was used.  Dissection began caudally, continued to both sides, and ended cranially. The laser enable contactless cutting and effective coagulation; hot forceps were occasionally used for hemostasis. The lesion was removed en block. Postoperative histology confirmed tubular adenoma HGD. Advantages: contactless coagulation and cutting, strong coagulation effect, energy is delivered locally, minimizing the lateral thermal damage, cost effective. Conclusion: thulium laser appears safe for colonic ESD thought further evaluation is needed.