Abstract: HIV-1 integrase catalyzes the integration of virus DNA into the host chromosome,which is a crucial step in viral replication.The inhibition of integrase activity is an effective measure to prevent HIV-1 replication.Moreover,integrase has no known functional analogue in human cells.Therefore,integrase becomes an ideal target for anti-HIV therapy.During the past decade,in vitro assays have been developed and applied to monitor the enzymatic activity of the integrase,study the reaction mechanisms of integase and screen integrase inhibitors in vitro.This review describes the recent development on integrase activity assays.