Background: Radon concentration was measured in the soil and indoor of Amman and Al- Rusaifa cities in Jordan during summer season. Materials and Methods: The measurement was performed using time-integrated passive radon dosimeters, containing a solid state nuclear track plastic detector, commercially known as CR-39. Results: Radon concentration levels in the soil ranged from 2.8 ± 1.2 to 6.9 ± 1.5 (kBq/m³) with an average  4.0 ± 1.6 (kBq/m³)  in Amman and  from and  6.5± 1.1 to  22.4 ± 5.2 kBq/m³  in Al- Rusaifa  with average 14.2 ± 2.5 (kBq/m³). The average indoor radon concentration in the first floor in Amman was 44.8± 5.3 (Bq/m³); while the average concentration in Al- Rusaifa, in the first floor, was 187± 16.35 (Bq/m³). In Al- Rusaifa, our results in the ground floor and the first floor were about 11% - 26 % higher than the reported values, while this ratio reaches to 56% of the soil.  Conclusion: The average indoor radon concentration indoor in Al-Rusaifa exceeds the action radon level recommend by WHO (100 Bq/m³). The potential health impact in this city is considered high. High radon level in Al- Rusaifa may be due to the phosphate content in its soil. A correlation between the radon concentration in the soil and indoor was observed