The main aim of the work was the biochemical analysis of the hippocampal formation tissue in the case of epileptic rats treated with the neuroprotective agent FK-506. Three groups of animals were compared: rats with pilocarpine induced seizures treated and non-treated with tacrolimus as well as naive controls. Synchrotron radiation Fourier transform infrared (SR-FTIR) microspectroscopy was used for the biomolecular analysis of studied samples. The measurements were carried out at SISSI beamline of ELETTRA. A Bruker IFS 66v/S interferometer coupled to a Bruker Hyperion 2000 microscope was used. The tissue samples were analyzed in transmission mode with a beam defined by a small aperture and spatial resolution steps of 10 mu m which allowed us to probe the selected cross-line of the sample at cellular resolution. The obtained results enabled to compare the distributions of proteins and lipids in the three hippocampal cellular layers, i.e. in molecular, multiform and granular layers. For epileptic animals both treated and non-treated with FK-506, the tendency for increase of the ratio of the absorbance at around 1548 and 1658 cm(-1) (amide II/amide I ratio) was observed, however only for the multiform layer these changes were statistically significant. Similar relation was noticed in case of the ratio of the absorbance at around 1631 and 1658 cm(-1). The mentioned results may suggest conformational changes of proteins in the direction of beta-sheet secondary structure. Additionally, a statistically significant increase in the lipid massif and a decrease of the ratio of absorbance at around 2921 and 2958 cm(-1) were observed for epileptic animals treated with tacrolimus comparing to the control group.