Monte Carlo calculations were done to simulate the decay of80mBr in order to estimate the energies and distribution of Auger and Coster-Kronig electrons emitted in this de-excitation process. Results show that for an isolated atom, the average number of electrons emitted per decay is 6.926 and 8.016 for an atom in the condensed state. These values agree well with experimental results of Wexler and Anderson. The average calculated electron energies were 1122 eV and 991 eV with ranges of 8.02 A° and 6.71 A° in unit density matter for the isolated an condensed states, respectively. These results will be used to estimate localized energy deposition which will be correlated to the radiotoxic effects of80mBr-bromo-deoxyuridine as measured in experiments currently underway in our laboratory using cell cultures. Our aim is to assess the radiotoxicity of low energy, short range electrons for its eventual use in cancer therapy.