Gamma ray spectra of natural radioactivity from 238U- and 232Th series and from 40K of eight (representing 40 collected samples) granite samples collected from Saint Katherine region, South Sinai, Egypt, had been measured using a gamma-ray spectrometer with an HPGe detector. The results reported in the present article include: Specific activities (A) of 226Ra, 232Th and 40K radionuclides, Radium equivalent activities (Raeq), external and internal hazard indices (Hext, Hint), external and internal level indices (Iγ, Iα), activity utilization index (I), exposure rate (ER) and other important parameters to the subject. The results have been presented in table graphs with the permissible maximum limits