CMV retinitis has had the most clinical importance of all the associated complications of AIDS. It is commonly seen in late stage AIDS, and even when treated has the potential to cause substantial loss of vision. CMV retinitis is also the most costly AIDS-related opportunistic infection; the mean monthly cost of treatment has been estimated at $7,825. The incidence of CMV retinitis has varied with changes in the therapeutic and prophylactic strategies for AIDS and its complications. It has been on the decline in recent years related to the increased use of highly active anti-retroviral therapy (HAART).