The indoor radon (222Rn) and thoron (220Rn) concentrations have been measured by using single-entry pinhole-based dosimetric technique, i.e., developed and calibrated at Bhabha Atomic Research Center (BARC), Mumbai, India, fitted with LR-115 solid state nuclear track detectors (SSNTDs) in the dwellings of Al-Zufli, Kingdom of Saudi Arabia (KSA). The concentration of 222Rn and 220Rn levels in the dwellings varied from 66.46 to 234.01 Bq.m−3 with a geometric means (G.M) of 121.19 Bq.m−3 and 1 to 211.55 Bq.m−3 with a G.M of 28.59 Bq.m−3, respectively. The annual effective dose (Deff) found to vary from 1.11 to 3.57 mSv.y−1 with a G.M of 2.01 mSv.y−1 and a standard deviation (S.D) of 0.55, respectively. The world average value of 222Rn and 220Rn and Deff are 100 Bq.m−3, 10 Bq.m−3, and 1 mSv.y−1, respectively. The lung doses from 222Rn and 220Rn exposure at various locations in study area are also studied. The dose rate to lungs (DLungs) varies from 2.66 to 9.36 nGyh−1 with a G.M. of 4.85 nGyh−1. The effective dose for lungs (DLeff) to tracheo-bronchial (DT-B) and pulmonary/ pulmonary lymph region (DP+PL), and lungs from 222Rn (DRL) varies from 3.19 to 11.23 nSv with a G.M of 5.82 nSv and 6.38 to 22.46 nSv with a G.M of 11.63 nSv, respectively. The 222Rn, 220Rn, and their progeny results are elevated in some cases mainly because of the poor ventilation conditions. Finally, it is recommended to the residents to improve ventilation system of the dwellings to avoid 222Rn, 220Rn, and their progeny accumulation. The prospective of the present study is to assess health risk caused due to inhalation of 222Rn and 220Rn by people living in the study area. Therefore, this study will provide baseline for further related studies.