Abstract: On purpose to examine Vester-Ulbricht hypothesis, i. e. , the origin of optical activity via parity nonconservation during the decay of certain radioactive isotopes. Since leucine has one of the larger g factor (the anisotropy factor) among the proteinaceous amino acids and Norden reported that the decar-boxylations of sublimed solid D -and L -leucine by γ rays give quite different quantum yields, indicating significant stereoselection but this effect vanishes by crystallization instead of sublimation. In this work we studied the beta radiolysis of sublimed D,L -leucine with 90Sr-90Y by using chirasil-val capillary column gas chromatography.The sublimed solid D,L -leucine was irradiated with 90Sr-90Y source for a total dose of 7. 56×104 Gy. The decomposition rates for three D,L -leucine samples are found to be 12. 8%, 14. 2% and 12. 5% and the corresponding G values are 125,139 and 122 respectively. The large G values of D,L -leucine suggest a.chain reaction. Within experimental error,the stereoselective radiolysis is not observed at thermodynamic equilibrium state. The further experiments are in progress.