Exposure to radon and its daughters is one of the important contributions for radiation doses to the publics. In this study, concentrations of radon gas were measured in air at Al-Tuwaitha Nuclear Site and some surrounding areas. Measurements were achieved by RAD7 (radon detector), manufactured by DURRIDGE COMPANY Inc. Indoor radon concentration plays a vital role in the total effective dose in the indoor environments. The measurement of the indoor radon concentrations ranged from (4.96±4.4 to 102±25) Bq/m 3 this high value of radon has been found at Decommissioning Directorate /emergency room, which is lower than the action value recommended by the EPA (Environmental Protection Agency) which is (148 Bq/m 3 ) while the lowest value has been founded in the Central Laboratories Directorate \ models Room. These values were used to calculate the annual effective dose, the dose exposed to the soft tissues other than the lungs D soft tissue , the dose rate due to alpha-radiation D lung and the effective dose equivalent rate H eff . The values of the annual effective doses for 222 Rn inhalation by the people were calculated and ranged from (0.124992 to 2.5704) mSv/y these result are lower than the value of (10 mSv/y) recommended by the ICRP (International Commission on Radiological Protection). It has been observed that winter concentration of indoor radon are greater than summer concentrations. The higher amount in the winter is attributed to the observation that people normally keep their windows closed during the winter, allowing indoor radon concentrations to rise. The lower radon concentrations in the summer might occur because people often open their windows, allowing low-radon outside air to enter the home. The results from this study show that the region has background radioactivity levels within the natural limits.