Herein, we report 2 cases of endophthalmitis after XEN Gel Stent implantation. A 68-year-old woman and an 80-year-old man had previously undergone uncomplicated XEN Gel Stent implantation for primary open-angle glaucoma 4 and 5 months prior, respectively. Both patients had presented with pain, redness, loss of vision, and sensitivity to light. For both patients, the best-corrected visual acuity was hand motion, eyelids and conjunctiva were hyperemic and edematous, anterior chamber had +3 cells and exhibited hypopyon, and B-scan ultrasonography revealed vitreous condensation. Blebitis was absent; the bleb height was medium, bleb width was 1 to 2 hours, and the bleb was avascular in the first case. In the second case, ∼2 mm of the XEN Gel Stent implant protruded from the conjunctiva; therefore, bleb formation was not observed. On a previous visit, the bleb height was medium, bleb width was 2 to 3 hours, and the bleb was mildly vascular. Both patients had undergone vitrectomy with silicone oil injection, but only the female patient had received intravitreal and topical antibiotics preoperatively. After surgery, both patients received topical antibiotic therapy. After 2 to 3 months, the silicone oil was removed; the final visual acuity remained low for the female patient (hand motion level). Despite immediate treatment, the final visual acuity may remain poor, similar to the outcome of patients with other types of endophthalmitis. It is important to provide the patients scheduled for XEN Gel Stent implantation information on the risk of infection and the other risk factors involved.