Reverse transcriptase-polymerase chain amplification reactions (RT-PCR) were used to identify transcripts for HIV-1 structural and regulatory proteins in peripheral blood mononuclear cells of a cohort of 48 patients. At least one set of PCR primers was capable of detecting HIV-1 transcripts in 94% of patients. Unspliced gag-pol transcripts were detected with gag or pol primer sets in 60 and 63% of samples, respectively. A significant inverse correlation was noted between transcript identification with the gag primer set and the number of CD4-positive lymphocytes in the blood sample and the clinical stage of infection. Single-spliced env transcripts were identified in 44% of individuals. Multiple-spliced tat or nef transcripts were detected in 6.2 and 53% of individuals, respectively. These findings indicate that viral transcripts are expressed throughout the course of HIV-1 infection.