Human Immunodeficiency virus (HIV) is the causative agent of Acquired Immunodeficiency Syndrome (AIDS). It is transmitted by sexual contact, infected blood or blood products or from mother to fetus. Within 3-6 weeks of exposure to the virus high levels of viremia can be detected in peripheral blood followed by HIV specific immune response leading to a decline in plasma viremia after 4-6 weeks of the onset of symptoms. Seroconverted individuals enter an asymptomatic phase that can last for years and show low level of viremia. Quantitation of HIV viremia shows that higher virus levels maybe correlated with increased risk of clinical progression to AIDS.