A series of novel 2-(phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones have been designed and synthesized. All of the new compounds were evaluated for their anti-HIV activities in MT-4 cells. Most of these new compounds showed moderate to potent activities against wild-type HIV-1 with an EC(50) ranging from 4.48microM to 0.18microM. Among them, 2-[(4-bromophenylamino)carbonylmethylthio]-6-(2,6-dichlorobenzyl)-5-methylpyrimidin-4(3H)-one 4b3 was identified as the most promising compound (EC(50) = 0.18+/-0.06microM, CC(50) >243.56microM, SI >1326). The structure-activity relationship (SAR) of these new congeners is discussed.