The effects of invert soaps with sodium hydroxide on infectious bursal disease virus (IBDV) were studied. Didecyldimethylammonium chloride was most effective, followed by alkylbenzyldimethylammonium chloride and [mono-bis(tri-methylammonium-methylene chloride)]-alkyl (C9-15) toluene. Dilutions without NaOH had little effect on virus titer. Didecyldimethylammonium chloride was further tested for its effects on IBDV by varying temperature, concentration of invert soap, and pH of the dilution. The effect of the invert soap was strong at 40 C, moderate at room temperature, and weak at 4 C. The concentration of invert soap influenced its efficacy at room temperature but not at 4 C. At pH values below 12.9, the invert soap showed decreased efficacy.