The radon concentrations in the groundwater, tap water samples and soil gases of the residential areas and forested lands of Uludağ were measured to research on the dynamics of low-high radon levels over the various rocks types found in this area. Besides, the annual effective doses for groundwater and tap waters were calculated and compared with the recommended dose value by the World Health Organization (WHO) to evaluate the health risk of inhabitant. The radon concentrations in water samples for the wet and dry seasons were found in the ranges of 0.17 ± 0.09 - 195.64 ± 6.87 Bq l-1 (median value of 5.13 Bq l-1) and 0.04 ± 0.01 - 199.24 ± 6.54 Bq l-1 (median value of 4.33 Bq l-1), respectively. Elevated radon concentrations were measured in the waters draining through igneous rocks (granite and granodiorite), known as uranium-rich rocks. The average radon and thoron concentrations of soil gases were found to be in the ranges of 0.65 ± 0.01 – 199.66 ± 3.27 kBq m-3 and 4.36 ± 0.36 – 245.9 ± 7.26 kBq m-3, respectively. The highest and lowest radon and thoron concentrations in soil gases were observed in the granitic area and in scree region, respectively.