The polymerase chain reaction (PCR) and reverse transcription were used to assess human immunodeficiency virus type 1 (HIV1) RNA expression in peripheral blood mononuclear cell samples from seropositive subjects. HIV RNA was detected from seropositive subjects who had no symptoms, lymphadenopathy syndrome, and acquired immunodeficiency syndrome. DNA PCR of the samples used for RNA extraction showed that seventeen of eighteen (94%) contained HIV proviral DNA. Eleven (65%) of the seventeen DNA-positive samples were also positive for HIV RNA, including samples from four patients undergoing antiviral drug treatment. Serum HIV antigen assays detected only six (32%) of the nineteen PCR-positive samples. Owing to the speed and high sensitivity of PCR for HIV detection, this technique will be suitable for monitoring antiviral therapy and the virus load of people with HIV infections.