Primary HIV-1 infection is frequently identified as a nonspecific viral syndrome occurring within 20 days to 8 weeks following a documented HIV exposure. However, symptoms vary from person to person, and some people undergo asymptomatic seroconversion. Because of the difficulty identifying patients with either acute HIV infection (within 30 days of initial infection) or early infection (within 12 months of initial infection), no systematic review of viral dynamics or immunodynamics in this patient population has been undertaken. A better understanding of the virologic and immunologic parameters during acute and early HIV infection should provide information relevant to the optimal design of future clinical therapeutic trials.