Аннотация:The morphometric analysis has revealed that in fleas from the contaminated by radionuclide territory (Bryansk Province, Vyshkovo) the variation of dimensions of some organs is greater than from the control one (Bryansk Province, Katolino). In the irradiated fleas Ctenophthalmus agyrtes, C. uncinatus, C. assimilis, Mega-bothristurbidus an atypical form of abdominal tergites, their unusual position with respect to sternites, and a
number of micromorphological alterations in integument have been found for the first time.