A method for detecting human immunodeficiency virus type 1 (HIV-1) provirus DNA in lymphocytes with improved sensitivity and reproducibility was developed using the polymerase chain reaction (PCR). Amplified HIV-1 DNA was hybridized with a 32P-labeled probe and quantitated with a beta-scanner after electrophoresis. A linear relationship was obtained between the common logarithms of the counts detected and the number of HIV-1 DNA copies applied to the PCR. Detectability was from 3 copies/10(5) lymphocytes, and linearity was maintained from 10 to 10(3) copies. HIV-1 DNA was detected in all 9 asymptomatic carriers tested (18 to 2,857 copies/10(5) CD4+ T lymphocytes). The viral burden was inversely related to the CD4+ lymphocyte count, suggesting that quantitation of provirus levels may serve as a predictor of progress in early HIV infection.