Abstract: Radium is naturally occurring radioactive element in the earth’s crust. Activities of the naturally occurring radionuclides 222Rn,226Ra and 228Ra were determined in drinking water consumed in Qassim area, Saudi Arabia. Twenty-four drinking water samples were collected from local markets and wells. Radon and radium concentrations were measured using RAD7 and gamma spectrometry preceded by ion exchange chromatography separation. The average concentration values of 222Rn in all samples were lower than 11 Bq L–1, the acceptable action levels for radon recommended by the US-Environmental Protection Agency. The average values for 226Ra in bottled, treated and well water were below the recommended level of 226Ra (27 pCi L–1), however, the average values for 228Ra in treated and well water were higher than the recommended level of 228Ra (2.7 pCi L–1). These recommended levels quoted from Saudi standard for drinking water. Where, when compare with US-EPA, it is observed that, 58% from the investigated samples (14 from 24) exceed 5 pCi L–1 recommended by the US-EPA and can do not safe to use in drinking.