A 50-year-old man presented to the ophthalmology clinic with a large lesion on his left eye that had developed over the preceding month. Physical examination showed a red, mobile, nodular mass on the inferior bulbar conjunctiva (Panel A) and violaceous plaques on the patient’s back and lower limbs. Antibody testing for human immunodeficiency virus (HIV) type 1 was positive. The viral load was 147,000 copies per milliliter (reference range, <40), and the CD4 cell count was 116 per cubic millimeter (reference range, 500 to 1200). A biopsy specimen of the skin showed a spindle-cell neoplasm, and immunohistochemical testing for human herpesvirus 8 was positive. These findings were consistent with Kaposi’s sarcoma, a malignant vascular neoplasm that is related to human herpesvirus 8 infection and that typically occurs in patients with immunodeficiency. Rapidly enlarging vascular or bleeding lesions in the eye in a patient with HIV infection should alert physicians to a possible diagnosis of conjunctival Kaposi’s sarcoma. Antiretroviral therapy and doxorubicin were initiated. Five months after presentation, the conjunctival mass had resolved (Panel B), as had the skin lesions.