Using a single colour fluorescence in situ hybridisation technique, dose-responses were derived for a range of chromosomally aberrant cell types and categories of aberrations induced in peripheral blood lymphocytes by alpha-particle radiation and analysed in their first in vitro division. For a range of doses that resulted predominantly in targeted cells receiving a single hit, i.e. 0-200 mGy, linear models fitted all the different categories of aberrant cells and aberration types but the profile of chromosome damage differed for 500 mGy, reflecting the effect of different track structure.