[ $7{eta}$ ]-Hydroxycholesterol (cholest-5-ene-3, 7-diol, $7{eta}$-OHC) showed the cytotoxicity on human cervical carcinoma cells (HeLa), $10{mu}M$ of 50% inhibitory concentration. We evaluated $7{eta}$-OHC as the possibility of radiation sensitizer. The combination effect of $7{eta}-OHC;and;{gamma}$-irradiation was measured using colony forming assay and flow cytometer with propidium iodide and $DiOC_6$ stained cells, respectively. The combined treatment of $7{eta}-OHC;and;{gamma}$-irradiation did not show significant enhancing effects on HeLa cells.