Abstract: A novel series of antidotes against organophosphorus poisoning having both anti-muscarinic activity and reactivation potency, were synthesized and evaluated for their pharmacological efficacy.The compounds are bisquarternary oxybismethylene(or:trimethylene)-bis-N-heterocycles.The N-heterocycles are comprised of 2,3 or 4 mono-substituted pyridines, 3-substituted quinuclidines and 4-substituted N-methylpiperidines (exclusive of both groups in one molecule designating a substituted pyridine ring). Some of the compounds display a remarkably low acute toxicity in mice.These antidotes have been shown to be effective against poisoning by a variety of organophosphorus compounds as well as carbamates. The compounds are also of value as active ingredients in ophthalmic preparations.