Aqueous antimicrobial compositions which comprise a halogenated amide antimicrobial, such as 2,2-dibromonitrilopropionamide, a water miscible organic solvent such as a straight chain polyalkylene glycol (e.g., polyethylene glycol 200) or an ether thereof (e.g., a mono- or di-lower alkyl and/or phenyl ether) and water are stabilized against decomposition of the halogenated amide antimicrobial by the addition of an azine or nitrile stabilizer, such as s-triazine-2,4,6-triol (i.e., cyanuric acid), 2-chloro-4,6-(ethylamino)-s-triazine, succinonitrile, cyanoguanadine, etc. The compositions, so stabilized, exhibit reduced rates of decomposition of the halogenated amide antimicrobial relative to the corresponding non-stabilized aqueous compositions.