Therapeutic effect of the glucoside extracted from the root of Astragalus Membranaceus (AM) was studied in guinea pigs intoxicated with 600 mg/kg doses of Dimethoate (D). Four groups of guinea pigs, each consisting of two males and two females, were treated with (a) D, (b) D + Atropine, and (c) D + AM, (d) D + Atropine + AM. The survival time of the animals increased from an average of 70 minutes without AM to an average of 235 minutes with AM. Severe changes in ECG were observed prior to respiratory distress in groups without AM, and Atropine did not modify such changes. Differently, severe ECG disorders appeared only after respiratory distress in groups treated with AM. Prolongation of the Q-T interval and changing of the T wave configuration were significantly mitigated in the AM treated animals, while, arrhythmias were minimized and postponed. Moreover, muscular fasciculation and fibrillation, seizures and secretion in the respiratory tract were also significantly reduced by AM treatment. Results have shown that AM could be a promising drug to be used after cholinergic crisis in the treatment of cardiac complications with severe organophosphate intoxication.