Samples of bovine serum albumin in H(2)O and D(2)O solutions, in the absence or presence of trehalose, were exposed separately to a static magnetic field at 200 mT and to a SO Hz electromagnetic field at 1.8 mT, studying the relative effects on the secondary structure of the protein by means of Fourier transform infrared spectroscopy. The spectra acquired in the mid-infrared region after 2 and 4 h of exposures to the static magnetic field showed a decrease in amide A and amide I band intensities for the protein in bidistilled aqueous solutions that was also evidenced after exposures to a 50 Hz electromagnetic field. These results led us to conclude that electromagnetic fields of low intensities can affect the C=O and C-N stretching vibrations and N-H plane bending of peptide linkages. Furthermore, mid-infrared spectra of bovine serum albumin in trehalose aqueous solutions were not significantly modified after the exposures, confirming the hypothesis of the possible bioprotective effectiveness of trehalose against electromagnetic fields.