<p>The naturally occurring radioactive gases radon (²²²Rn), thoron (²²⁰Rn) and their decay products contribute approximately 50% of the ionizing radiation dose received by the human population. The present paper reports on a systematic approach to estimate the indoor radon, thoron and their progeny concentration along with the inhalation dose in the Thoubal district of Manipur, a north eastern state of India. Sixty dwellings of different types such as mud, concrete and semi pucca houses have been selected from 13 different villages of the district after conducting a preliminary survey of outdoor gamma exposure rate using a gamma survey meter. Pin hole-based twin cup dosimeters and deposition-based direct radon/thoron progeny sensors (DRPS/DTPS) were used for time integrated passive measurements of radon/thoron concentration and the progeny concentrations, respectively. The dosimeters were deployed in the selected houses during three different seasons comprising of four months viz., summer, winter and rainy season. The observed values were used to determine the total annual effective inhalation dose. Seasonal variation was observed in the measured parameters with winter season showing the highest radon and thoron concentrations. Variation was also observed in the different types of dwellings. This study is the first reporting the results of such measurements in this region and may serve as a foundation for further research and investigations.</p>