In an ongoing effort to develop novel non-nucleoside human immunodeficiency virus inhibitors, a series of substituted 2-(1H-benzimidazol-2-ylamino)pyrimidin-4(3H)-ones and related derivatives were synthesized via cyclocondensation of 2-ganidino-1H-benzimidazole with diethyl ethoxymethylenemalonate, substituted diethyl malonates, some beta-keto esters and 2-acetylbutyrolactone. From these series of compounds, 2-(1H-benzimidazol-2-ylamino)-6-hydroxy-5-phenylpyrimidin -4(3H)-ones (5f, NSC 666286) was confirmed to have a moderate in vitro anti-HIV activity.