Purpose: To describe a case of massive spontaneous subconjunctival hemorrhage in a patient taking warfarin with a therapeutic international normalized ratio (INR). Observations: Massive circumferential hemorrhagic chemosis, extensive periorbital and facial ecchymosis, and active arterial extravasation in the subconjunctiva which required cessation and reversal of anticoagulation. Findings gradually resolved over several months after discharge. Conclusions and importance: While subconjunctival hemorrhage, even in anticoagulated patients, is usually benign, rare examples of severe presentations exist. We present, to our knowledge, the first documented case of a subconjunctival hemorrhage necessitating cessation and reversal of anticoagulation in the setting of a therapeutic INR.