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 and which have improved stability are obtained by ensuring that such compositions are substantially free of glycols having a molecular weight of less than about 70 and of salts of organic acids. The resulting improved compositions exhibit reduced rates of decomposition of the halogenated amide antimicrobial relative to the corresponding aqueous compositions containing salts of organic acids and/or glycols having a molecular weight of less than about 70.