A quantitative study has been made of the radiochemical decomposition of trypsin by the radiations from radium emanation. The following equation accounts quantitatively for the experimental results presented. See PDF for Equation It follows from this that the amount of trypsin decomposed by the radiations from radium emanation depends on the concentration of trypsin present and is proportional to the quantity of emanation expressed in millicuries and to the time of irradiation expressed in hours. It would seem that it is the active or undissociated trypsin that is affected. Evidence has been found which suggests that the beta radiations produce the decomposition observed for which the above statement holds. Qualitative evidence has been found which suggests that x-rays, gamma rays, and beta rays produce identical effects in dilute trypsin solutions.