The effects of interaction of ethanol, l-butanol or t-butanol peroxyl radicals with oxyhemoglobin (HbO2) were estimated using absorption spectroscopy in the visible range and tryptophan fluorescence. Peroxyl radicals were generated by gamma-radiation. Alcohol peroxyl radicals showed the same effectiveness in oxidizing HbO2 iron as -OH radicals (GFe(III) = 1.8 for a dose 0.33 kGy). However, they degraded hemoglobin to hemichromes and cholehemichromes to a lesser degree than -OH radicals. In addition l- and t-butanol peroxyl radicals were less effective than peroxyl ethanol radicals. Alcohol peroxyl radicals caused unfolding of protein to a much lesser degree than -OH radicals. Their contribution to the destruction of tryptophan residues was nearly matched by those obtained with the -OH radicals.