A 47-year-old man was treated with one session of endoscopic cyclophotocoagulation for uncontrolled, elevated intraocular pressure. Before treatment, the eye was quiet and uninflamed. Pretreatment visual acuity was 4/200 and the intraocular pressure was 24 mm Hg. Treatment was applied to the ciliary processes for nearly 360 degrees. During the postoperative follow-up, the patient developed eye pain and persistent ocular inflammation. This ultimately led to phthisical changes evident 5 months postoperatively, when visual acuity was 1/200 and the intraocular pressure was 7 mm Hg. Eighteen months after endoscopic cyclophotocoagulation, visual acuity was light perception and intraocular pressure was less than 1 mm Hg. Phthisis is among the complications that may result after treatment with endoscopic cyclophotocoagulation.