The morphometric analysis has revealed that in fleas from the contamin
ated by radionuclide territory (Bryank province, Vyshkovo) the range o
f dimensions in some organs is greater than in fleas from the control
(Bryansk province, Katolino), In the irradiated fleas Ctenophthalmus a
gyrtes, C. uncinatus, C. assimilis, Megabothris turbidus an atypical f
orm of abdomen tergites, their unusual position with respect to sterni
tes, a number of micromorphological alterations in integument have bee
n found for the first time.