Six patients with the acquired immunodeficiency syndrome had frosted periphlebitis associated with large areas of cytomegalovirus retinitis. Following the administration of ganciclovir, periphlebitis resolved within 2–6 weeks concomitant with quieting of cytomegalovirus retinitis. Frosted retinal periphlebitis in the acquired immunodeficiency syndrome is associated with cytomegalovirus retinitis in North America. Medical treatment of cytomegalovirus retinitis leads to resolution of the periphlebitis without the need for systemic corticosteroids.