The viral enzyme, HIV integrase (MW 32 kDa), is one of the three key enzymes of the pol gene of HIV. HIV integrase is involved in the integration of HIV DNA into host chromosomal DNA. There is apparently no functional equivalent of this enzyme in human cells. Integration of HIV DNA into the host cell genome apparently occurs by a carefully defined sequence of DNA tailoring (3-processing) and coupling (joining or integration) reactions. In spite of some effort in this area targeted at the discovery of therapeutically useful inhibitors of this viral enzyme, there are no drugs for HIV / AIDS in clinical use where the mechanism of action is inhibition of HIV integrase. It is clear that new knowledge on inhibitors of this enzyme is of critical importance in the anti-HIV drug discovery area. This review focuses on the major classes of compounds that have been discovered as inhibitors of HIV integrase. Some of these compounds are non-specific inhibitors of the enzyme while evidence suggests that others may possess some specificity. The various classes include nucleotides, oligonucleotides, dinucleotides, and miscellaneous small molecules including heterocyclic systems, natural products, diketo acids and sulfones. A major focus of the review is on discoveries from my laboratory in the area of non-natural, nuclease-resistant dinucleotide inhibitors of HIV integrase.