DNA integration appears to be an obligatory step for the efficient replication of retroviruses. Studies of the integration reaction for the avian and murine C-type retroviruses have defined the importance of: i) LTR terminal sequences, which are joined to host DNA, and ii) the activity of the retroviral integration protein (IN). The specific requirements for the integration of HIV DNA have not yet been defined. In this review, we survey studies pertinent to this reaction for HIV and extrapolate a mechanism for HIV DNA integration based upon knowledge of the integrative recombination reaction of the C-type retroviruses.