The effects of gamma-radiation on the dielectric properties of Au/Si3N4/n-Si/Au (MIS) structure with Si3N4 thin film prepared by r.f. magnetron sputtering were investigated by using capacitance-voltage and conductance-voltage measurements. The capacitance (C) and conductance (G) measurements were performed at five different frequency values (1, 10, 100, 500 and 1000 kHz) before and after irradiation in the radiation dose range of 2 kGy to 100 kGy. The dielectric parameters of the MIS structure such as dielectric constant (epsilon'), dielectric loss (tan delta), loss tangent (tan delta), ac conductivity ((sigma(ac)) and electric modulus (M) were calculated from these measurements. The measured value of C and G decreases with increase in radiation dose and frequency. After irradiation, the decrease in capacitance is due to the irradiation-induced defects at the interface. Also, the calculated value epsilon' of the epsilon" and decreases with the increase of radiation dose and frequency. In addition, while the value of sigma(ac) decreases with the increasing radiation dose, it increases with the increasing frequency. As a result, the dielectric parameters of the structure are quite sensitive to radiation.