Several 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives 13-28 and 35-44 have been synthesized and tested as potential HIV-1 integrase (IN) inhibitors. Compounds 15-17, 19, 21-28, 36 and 41 inhibited IN with IC(50) values in the range of 3.3-63.0 microM. The compounds 13, 15, 16, 21-24 and 26-28 were further tested at the US National Cancer Institute for their in vitro activity