Background: One of the most significant radionuclides in natural drinking waters is ²²⁶Ra and its decay products. It is potential of health problems, including cancer risk. In this study, the effect of ²²⁶Ra concentration in 28 drinking water samples collected from the North Guilan province was investigated. Materials and Methods: The activity concentrations of ²²⁶Ra were measured by using of radon emanation method and Pylon AB-5 radon scintillation detector. The annual effective dose distribution by age groups, radiological risk and chemical toxicity risk were calculated in drinking water.  Results: The activity concentration results range from a low limit of detection (LLD) 2.0±0.1 mBq l^-1 to 38.2±2.4 mBq l^-1. Also, the annual effective dose distribution by age groups estimated results were from 1.8×10^-6 Sv y^-1 for adults to 1.5×10^-5 Sv y^-1 for infants.  The radiological risk assessment results were 1.06×10^-6 to 2.03×10^-5 for morbidity risk, 7.32×10^-7 to 1.40×10^-5 for mortality risk. The chemical toxicity risk results obtained from 1.08×10^-1 to 5.63×10^-3. Conclusion: The activity concentration level of ²²⁶Ra in all drinking water samples were less than the recommended level WHO for drinking water 1000 mBq l^-1. Meanwhile, annual effective dose level, cancer morbidity, mortality risk and life annual daily dose due to consumption of selected drink water samples were less than the standard limit.