In present investigation, Solid State Nuclear Track Detectors (SSNTDS ) based twin chamber dosimeter with LR-115 track detector were used for estimating Radon (222Rn) and Thoron (220Rn) gas concentration levels in the dwellings of Jaipur city. Radon and thoron concentration levels in the studied dwellings were found to vary from 4.6 to 27.4 Bq m-3 and thoron concentrations is found to vary from 3.8 to 22.9 Bq m-3. The annual effective dose due to the exposure to radon and progeny was found to vary from 0.13 to 0.79 mSv whereas from thoron found to vary from 0.09 to 0.57 mSv.