Ionization frequency distributions for 1-4 MeV protons were calculated using Monte Carlo techniques for an absorber site having an effective diameter of 250 nm (unit density material). For proton tracks passing through the absorber site, the calculated frequency distributions, mean ionization and relative variance agreed very well with experiments. The Monte Carlo method, employing sophisticated source terms, apparently can be used effectively to calculate ionization and energy deposition in sites too small for experimental techniques.