G. Gattar is located in the northern part of the Eastern Desert of Egypt, bounded by latitudes 26° 52´ - 27° 08´ N and longitudes 33° 13´ – 33° 26´ E and covers an area of about 178 km2. Eighteen samples, nine from uraniferous and nine from mineralized granites were measured radiometrically for 238U, 232Th, 226RaeU and 40K determination by Na-I detector and the radioactive minerals identified by alpha track method. Based on the petrography, radioactive mineral content and radioactivity, Gattarian granites were classified into uraniferous and mineralized granites. Uranium contents reach up to 229 ppm in the uraniferous granites and to 20300 ppm in the mineralized granites, which is extremely higher than the international limits. eTh/eU ratio of the studied uraniferous and mineralized granites show average ratios of 0.05 and 0.0044, respectively, which is extremely lower than the average of igneous rocks, suggesting uranium enrichment in reducing conditions. The uraniferous and mineralized granites U/Th ratios average are 62.23 and 4234.45, respectively, indicating that the studied two granitic types are considered highly productive rocks. The radioelements interrelations manifest that the distribution of radioelements not only magmatic but also related to hydrothermal redistribution of radionuclides associating with uranium deposition. The radiological hazard parameters, such as the dose rate (D), the annual effective dose equivalent (AEDE), radium equivalent activity (Raeq), external (Hex), internal (Hin) hazard indices and gamma index (Iγ) were estimated for these granites and compared with the international levels. Nearly, all the studied samples are to a great extent higher than the recommended permissible levels for all environmental parameters.