#$%^&*AU2013231143B220160519.pdf#####ABSTRACT A synergistic antimicrobial composition comprising: (a) ortho-phenylphenol or its alkali metal or ammonium salts; and (b) tris(hydroxymethyl)nitromethane; wherein a weight ratio of ortho-phenylphenol or its alkali metal or ammonium salts to tris(hydroxymethyl)nitromethane is from 15:1 to 1:15.