A series of benzimidazole-4, 7-diones bearing at the 2-position the thiomethyl group or the 2- pyridyl moiety has been synthesized and tested in vitro on three tumor cell lines. Two of them show a very good antiproliferative effect. Compounds 1 and 2d are more active or equiactive, respectively, than MMC against human lymphoblastic leukemia. Both compounds exhibit high activity on human non-Hodgkin lymphoma. Compound 1 is non ...