The process of accumulation of absorbed doses from incorporated 137Cs in the body and gonads of male mice was investigated in our experiments. The radionuclide accumulated in gonads has very long time of excretion, and as result the radionuclide can be treated as long lasting and permanent source of alpha- and beta-radiation in gonads. The rates of total exposed doses in gonads were in 2.0-3.0 times higher then the average total exposed dose in hole body.