Ionizing radiation has been proved a major stress that can induce carcinogenesis. Among these ionizing radiations the most significant one is radon which is a source of 43% of the annual dose averaged over the population of the world. If it is present in enhanced level beyond maximum permissible limit, it may cause lung cancer. In the present work a set of indoor radon measurements has been carried out in some houses of Debresina district, Ethiopia using cellulose nitrate LR-115 type-II plastic track detectors in the bare mode. The detectors were fixed in the houses for one month to be exposed with indoor radon from February to March 2018. Etching of detectors was done with 2.5 N NaOH solution for 75 minutes at 60°C in the Soil physics laboratory and counting of tracks recorded was done using optical microscope in the Department of Earth Science, Bahirdar University. It is found that the value of radon concentration in those dwellings ranges from 12.24 to 251.94 Bq/m 3 with an average of 102.87 Bq/m 3 and standard deviation of 81.97 Bq/m 3 . The annual effective dose rates are found to vary from 0.31 to 6.29 mSv y −1 with an average of 2.57 mSv y -1 and a standard deviation of 2.05 mSv y −1 . The indoor radon concentration has been found to have strong correlation with the ventilation condition. Ventilated houses have shown less radon concentration than unventilated houses. Though most of the indoor radon concentration values measured are well within the recommended action level of ICRP, more than half of these values are above the new recommended level of WHO.