© 2019, Editura Academiei Romane. All rights reserved.In the present study, the indoor radon activity concentrations in air were measured by using the LR-115 solid state nuclear track detectors in 25 dwellings (chosen as 9 old and 16 new) in Muğla, Turkey. The indoor radon activity concentration values for old dwellings vary from 160.37 to 367.54 Bq/m3 and for new dwellings from 79.83 to 347.41 Bq/m3. Moreover, the gamma-ray activity measurements of 238U, 232Th, 40K and 137Cs has been measured by using a HPGe detector for sand and sediment samples which were collected from Muğla. The activity concentration values for 238U, 232Th, 40K, and 137Cs vary from 5.6 to 72.6 Bq/kg, 2.26 to 38.03 Bq/kg, 79.54 to 867.48 Bq/kg and 0 to 1.42 Bq/kg, respectively. Most of the activity and effective dose values were within the limits of United Nations Scientific Committee on the Effects of Atomic Radiations (UNSCEAR) reports. In addition, a comparison between Muğla and other cities specified in the literature was also given.