Radon monitoring has been increasingly conducted worldwide because of the hazardous effects of radon on the health of human beings. In the present research, groundwater samples were taken from hand pumps at different areas of the districts of SriGanganagar, Hanumangarh, Sikar and Churu in northern Rajasthan. RAD7, an electronic radon detector (Durridge co., USA), was used to estimate the radon concentration in groundwater used for drinking. Radon concentration in the groundwater ranged from 0.5 ± 0.3 Bq l(-1) (Chimanpura) to 85.7±4.9 Bq l(-1)(Khandela) with an average value of 9.03±1.03 Bq l(-1). In 89 % of the samples, radon concentration is well below the allowed maximum contamination level (MCL) of radon concentration in water of 11 Bq l(-1), proposed by US Environmental Protection Agency (USEPA). Only in 11 % of the samples, the recorded values were found to be higher than MCL proposed by USEPA and only in 5 % of the samples, the recorded values were found to be higher than the values between 4 and 40 Bq l(-1) suggested for radon concentration in water for human consumption by the United Nations Scientific Committee on the effect of Atomic Radiation (UNSCEAR). The annual effective dose in stomach and lungs per person was also evaluated in this research. The estimated total annual effective dose of adults ranged from 1.34 to 229.68 µSv y(-1). The total annual effective dose from three locations of the studied area was found to be greater than the safe limit (0.1 mSv y(-1)) recommended by World Health Organization and EU Council.