We have established a simple system for measuring HIV-1 DNA load in CD4+ cells. In a multiplex configuration, a conserved region in the HIV-1 pol gene and a section of the human albumin gene were simultaneously amplified to estimate the number of HIV-1 DNA copies per cellular genome. An established Epstein-Barr virus (EBV) standard system was used to calibrate the HIV-1 quantification. Our multiplex PCR system was tested on different in vitro developed HIV-1 strains and on longitudinal samples from eight patients. The system was able to amplify both in vitro and in vivo samples of various genetic compositions. In all eight patients, HIV-1 DNA was detected and ranged between 0.17 and 51×10−3 copies per CD4+ cell and could be monitored longitudinally, including long-term PI-ART and STI. The measured HIV-1 DNA load may be used to select the best time for the institution or re-institution of therapy.