We studied two patients, a 43-year-old Hispanic man with a one-year history of acquired immunodeficiency syndrome (AIDS) and a 34-year-old Hispanic man with newly diagnosed AIDS. Both had necrotizing retinitis that progressed to panophthalmitis and orbital cellulitis. Toxoplasmosis was not diagnosed in the first patient early in the course of the disease. The second patient had a history of toxoplasmic retinochoroiditis. Despite anti-toxoplasmosis therapy, visual acuity deteriorated to no light perception in both patients. Diagnostic biopsy of the eye wall was performed on the first patient and enucleation of the globe on the second. Toxoplasmic panophthalmitis and orbital cellulitis were diagnosed in each patient by light microscopy and confirmed by electron microscopy. When patients with AIDS develop necrotizing retinitis, toxoplasmosis must be considered in the differential diagnosis, along with cytomegalovirus retinitis, progressive outer retinal necrosis, and syphilitic retinitis. Unlike cytomegalovirus retinitis, progressive outer retinal necrosis, and syphilitic retinitis, however, toxoplasmosis can cause a progressive intraocular infection, panophthalmitis, and orbital cellulitis in patients with AIDS.