A series of N (1),N (2)-bis-[4-(t-amino)-2-butynyl]phthalamides have been synthesized and investigated for the blocking of the motor effect of oxotremorine in intact mice and for their antagonistic activity towards acetylcholine on isolated guinea pig ileum preparations. All N (1),N (2)-bis-[4-(t-amino)-2-butynyl]phthalamides showed more selectivity as oxotremorine antagonists than atropine and less potent than atropine on peripheral cholinergic antagonistic activity.