The effects of gamma irradiation on electrical parameters of Au/Si3N4/n-Si (MIS) structure were investigated by using the capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements. The MIS structure was irradiated using gamma-radiation source at a dose rate of 0.69 kGy/h. The C-V and G/omega-V measurements were carried out at a total dose range of 0-100 kGy for five different frequencies (1, 10, 100, 500 and 1000 kHz). The obtained results showed that the C and G/omega values decrease with the increasing radiation dose due to the irradiation-induced defects at the interface. Also, the observed decrease in the C and G/omega values with the increasing frequency was explained on the basis of interface states (N-ss). The values of series resistance (R-s) increase with the increasing radiation dose. To obtain the real capacitance and conductance of the capacitor, the measured values of C and G/omega were corrected to eliminate the effect of series resistance. The values of N-ss were determined by using the conductance method and were decreased with the increasing radiation dose.