Unilateral agenesis of the lacrimal puncta and enlargement of the lacrimal canal in adults are rare anatomic variants. We herein report a case of a 34-year-old woman with a unilateral dacryocystocele and lacrimal puncta agenesis. The patient had a long history of epiphora and visited the author's clinic for evaluation of a mass in her right medial canthal area that had been growing for the last 2 months. This article reports the results of the author's physical examinations, magnetic resonance imaging findings, and surgical treatment comprising dacryocystorhinostomy with silicone tubes. Six months after surgery, the patient's symptoms improved.