Human immunodeficiency virus type 1 (HIV1) RNA was quantitated in the plasma of HIV1-seropositive patients using a simplified guanidinium-based extraction technique, reverse transcriptase (RT) and the polymerase chain reaction (PCR). Plasma samples were obtained from 15 HIV1-seronegative individuals and 38 HIV1-seropositive patients. Following the extraction of RNA from plasma using "RNAzol", HIV1 RNA was reverse-transcribed using random hexamers, amplified by PCR and then detected by solution oligonucleotide hybridization. Of the 15 HIV1-seronegative individuals, 14 were negative for HIV1 RNA by RT-PCR. One high-risk patient who was HTLV-I-seropositive but HIV1-seronegative was found to be positive for HIV1 RNA by RT-PCR. All 38 HIV1-seropositive patients were positive for HIV1 RNA by this technique. The HIV1 RNA levels in plasma varied from 800 to 500,000 copies/ml. Patients with advanced clinical disease tended to have HIV1 RNA levels above 25,000 copies/ml. In patients studied serially, an increase in plasma HIV1 RNA correlated with a progressive decline in CD4+ T cells and a deteriorating clinical course. The simplified quantitative RT-PCR assay for HIV1 RNA provides a useful tool for the evaluation and management of HIV disease.