The HIV epidemic continues to spread worldwide, particularly among women and nonwhites. Development of vaccines and improved treatments depend on understanding pathogenesis. In the past few years, studies have begun to focus on HIV-1 pathogenesis in women, in whom some differences have been found in comparison with men. Attention is now focused on HIV-1 infection in reservoirs other than blood, particularly the genital tract. In addition, study of the genetic determinants of susceptibility to HIV-1 infection, including the chemokine receptors, have provided knowledge useful for the design of new treatments.