[en] Attempts to explain dose-effect relationships for neutron radiations in terms of microdosimetric parameters (in the widest sense) based on calculation require charged particle fluence spectra to be computed. An initial approach to the problem would be to look for relationships between dose-effect curves based purely on these spectra. This is now possible because of the recent developments of computer programs by Caswell and Coyne and Edwards and Dennis. Using the data of Barendsen for Tl kidney cells and Lloyd for lymphocytes some general conclusions may be drawn about gross sensitive volume and the relative effectiveness fo different particles for cell killing as a function of energy