The toxic effects of ethanol on bovine serum albumin (BSA) were measured by resonance light scattering (RLS), fluorescence spectroscopy, ultraviolet spectrophotometry (UV), circular dichroism (CD), and transmission electron microscopy (TEM). The results indicated that ethanol had toxic effects on BSA, which led to protein denaturation and the effects increased with the ethanol dose. By means of RLS, BSA was found to aggregate in the presence of ethanol and particles smaller than 100 nm were observed from TEM. The fluorescence spectra showed that the intensity of the characteristic peak of BSA decreased and blue shifted, because of changes in the BSA skeleton structure, as well as alteration of the microenvironment of tryptophan (Trp) residues. The conformation changes of BSA were also shown by UV and CD spectrometry.