Indoor radon has been recognized as one of the health hazards for mankind because long-term exposure to radon increases the risk of developing lung cancer. This study aims at assessing the contribution of building materials towards the total indoor radon exposure to the inhabitants of Nablus district, Palestine. The radon exhalation rate has been carried out for different building materials of international origin used in construction in Nablus district. The “closed-can technique” has been employed in this study using solid state nuclear track detectors (CR-39). After 100 days of exposure, CR39 detectors were etched chemically and then counted under an optical microscope. Results show that Radon exhalation rates from granite and marble have relatively high values as compared to other building materials followed- in order- by cement, ceramic, concrete, building stones, and porcelain, while gypsum, sand, gravel and bricks contribute less to radon exhalation rate which was found to range from (55.37 ± 15.01) mBq/m 2 h for gypsum samples to (589.54 ± 73.24) mBq/m 2 h for granite samples, with a total average value of (268.56 ± 166.21) mBq/m 2 h. The corresponding radon concentration, effective radium content, and annual effective dose average values were (148.49 ± 91.13) Bq/m 3 , (1.93 ± 1.20) Bq/Kg and (3.74 ± 2.30) mSv/y, respectively. In general, the radon exhalation rate from the investigated building materials is low and under the global value except for granite, marble and some cement samples and thus except for the excluded, the studied materials are safe as construction materials.