The performance of a home made MIS-p-Si solar cell was experimentally studied under various gamma irradiation doses (up to 500 Mrad), The effect of radiation dose on the I-V and C-V characteristics was investigated in this work. The obtained results showed that all the output parameters of the cells under investigation were degraded with gamma radiation exposure. In addition, the effects of fabrication conditions (metal thickness and adding of antireflection coating) on the cell output parameters were also investigated.