In Reply.— Dr Murray's comments regarding CMV retinitis are timely and interesting. I agree with him that only a prospective serological study can determine whether CMV retinitis represents a primary or secondary infection. CMV retinitis is not a very common affliction, although it probably has not been adequately sought for. I do not have any preconceived ideas as to its pathogenesis. Cytomegalovirus retinitis may result from widespread viral dissemination during primary or secondary infection, or the retinitis may represent reactivation of a CMV infection in situ. Possibly, the virus is deposited during an early or even congenital infection and is activated when the patient is immunosuppressed. The retina may be a relatively uncommon, although well-known, site of primary infection, and this may account for the infrequency of CMV retinitis. Finally, I do not want our article to leave the impression that the triad of fever, leukopenia, and atypical lymphocytosis is