Abstract
Six patients are presented who died with active cytomegalovirus (CMV) encephalitis in whom brain MR scans within 25 days of death failed to reveal distinctive findings suggesting the diagnosis of CMV encephalitis. While MR scanning is crucial to evulation of AIDS patients developing neurologic complications, it is not sensitive to the presence of CMV encephalitis even when it is quite severe. The diagnosis of CMV encephalitis during life rests on characteristic clinical findings supported by typical laboratory measures including the presence of CMV DNA in cerebrospinal fluid as detected by polymerase chain reaction.