A series of (2-pyrimidinylthiomethyl)carbonitriles and -carboxamidoximes was synthesized and the antiarrhythmic effects were evaluated against ventricular arrhythmias as measured by the electrical fibrillatory threshold in the anesthetized dog. Structure-activity studies indicated 2-[4-(p-chlorobenzylamino)-6-methyl-2-pyrimidinylthio]acetamidoxime dihydrochloride (6a) and 2-[4-(1,3-benzodioxol-5-ylmethylamino-6-propyl-2-pyrimidinylthio]acetamidoxime (6g) to be the most potent members of the series.