HIV-1 viral load represents a basic marker for evaluation of the rate and severity of HIV-1 related disease and to monitor the effectiveness of treatment. An SYBR green-based real-time RT-PCR (SYBR green real-time RT-PCR) revealed by Light Cycler technology was evaluated for quantitation of HIV-1 RNA viral load in plasma of HIV-1 seropositive patients. The performance of the SYBR green real-time PCR was assessed on 56 HIV-1 seropositive patients under highly active retroviral therapy (HAART) and 25 blood donors. The results demonstrated that this technique detected 50 HIV-1 RNA copies per millilitre of plasma. Moreover, we compared real-time RT-PCR with the b-DNA technique considered widely a reference technique for HIV-1 RNA viral load measurement. The parallel quantitative analysis of HIV-1 positive samples showed a high correlation (r=0.908) between the two methods. Although b-DNA and the real-time-based method gave similar sensitivity, the assay determined quantitatively HIV-1 RNA copies in 4 out of 16 samples shown as undetectable by b-DNA. The SYBR green real-time RT-PCR represents a good alternative to b-DNA assay in HIV-1 viral load determination especially during the monitoring of HAART treatment.