HIV infection leads to loss of CD4 T cells and development of AIDS in most individuals without treatment. While disease progression during HIV infection correlates with the plasma viral load, much less is known about the levels of HIV vDNA. This paper describes the development and validation of a sensitive, quantitative PCR assay for the assessment of HIV vDNA. The system uses novel single tube, multiply competitive PCR technology, which allows five-point competitor competition in a single PCR reaction. The reproducibility and performance characteristics of the assay are extensively studied, which indicate that the system performs well in high DNA backgrounds. Using this assay system on a cohort of protease naive patients, HIV vDNA was assessed from PBMCs over an average follow-up period of 5 years. The data indicate that the HIV vDNA pool does not appreciably accumulate over the follow-up period, with many of the patients followed for up to 8 years. A reliable, quantitative assessment of vDNA pools will allow a better understanding of the dynamics of HIV pathogenesis. Copyright (C) 2000 Elsevier Science B.V.