Sheep were studied for the possibility of treatment after parenteral (intramuscular) intoxication with EDMM (methylthiophosphorous acid O-ethyl-S-2-dimethylamino-ethylester) and with EDIM (methylthiophosphorous acid O-ethyl-S-2-diisopropyl-aminoethylester). In both cases of intoxication, the therapy was based on a system of an anticholinergic and cholinesterase reactivator administered singly at a time of the maximum development of the clinical signs of poisoning and maximum inhibition of both erythrocytic (AChE, E.C.3.1.1.7.) and plasma (BChE, E.C.3.1.1.8.) cholinesterase. The optimum therapeutic system requires the administration of 20.0 mg atropine s. c. pro toto and 10.0 mg trimedoxim per kg 1. w. i. v. In both cases of poisoning with doses = LD50 in i. m. administration, the mentioned system was actually positive. In a single administration irrespective of the doses of the used drugs, the system does not guarantee survival after ingestion of anticholinesterasic doses above LD50.