[en] Full text: β-aminonitriles, the bi-functional compounds, that have a wide range biological and physiological activity. They found to be show a radioprotector effect, too. At first, b-aminonitriles were synthesised by one of the authors of this report in result of interaction of the ammonium and different amines with crotononitrile and metcrilonitrile. The radioprotector effect of the b-aminonitriles was studied using white male rats Vistar with mass 160-180 gm. The result of experiments was statistically treated and testified that b-aminobutironitrile, b-allilaminobutiroonitrile, b-diethylami-nobutironitrile and b-butilaminoizobutironitrile radioprotector effect is varied in different degree in accordance to doze, method of injection into animal's organism and due to structure changes. So, the theoretical investigations, based on the molecular mechanics calculations and experimental IR-spectroscopy were carried out. A great number (more than 10) available conformational states for each bi-functional compounds was observed. Theoretical calculations of their IR-spectra, i.e. frequencies and forms of normal oscillations and theoretical values of intensities of absorption bands were carried out. The set of force and electrooptic parameters has been received. b-aminonitriles IR -spectrum interpretation, the nature of each absorption band are analyzed. At the end, the theoretical curves of spectral distribution of the absorption coefficient for all calculated conformations are constructed. The summary curves with different combination of the conformers (in assumption of equal percent contents into investigated samples) are constructed, too. The conclusion on conformational conditions of the molecules was made on the base of comparison of the theoretical curves and experimental spectra. The result of investigations is correlated with the experimental study of b-aminonitriles radioprotector properties