Abstract: Darenthin and guanethidine are adrenergic neurone blocking agents. They are used for treatment of hypertension.In the present paper, the synthesis of four new quaternary ammonium salts and eight new guanidines of thiophene, furan and benzofuran were reported. Preliminary pharmacological tests revealed that most of them showed hypotensive activity, compound (Ⅱ-1), (Ⅴ-3) and (Ⅴ-7) being much stronger.The quaternary ammonium salts were synthesized from their Corresponding amines with ethyl p-toluenesulfonate and the guanidine derivatives from primary amines with methyl isothiourea.