The present work provides reasonable understanding to the effect of radiation on body water, blood viscosity and dielectric properties (conductivity and permittivity) of different rat tissues. The characteristic frequencies (fc) of irradiated rat tissues under study decrease with increasing post-irradiation time up to 16 days for liver and kidney and up to 9 days for muscle tissues then progressively approach near non-irradiated level at 30 days post-irradiation time. The variations in body water compartments demonstrate statistically significant difference in ICW (11.61% (P= 0.0001)) or ECW (9.95% (P= 0.0216)) values between non- irradiated and irradiated rats (600Rads). The changes in conductivity and permittivity between non-irradiated and irradiated rats (at 600Rads) for different rat tissues don't show statistically significant for liver (-17.10% (P = 0.1139)) and kidney (-2.91% (P = 0.6636)) where as the difference in conductivity values between non- and irradiated muscle tissues shows statistically significant (19.21% P= 0.0046). The comparison of non- and irradiated group tissues for both conductivity and permittivity values are observed to be increased with doses