In this study, the activity concentrations of gross alpha and gross beta in 125 drinking water samples (16 tap and 109 spring waters) collected from Ankara province were measured using a gas proportional alpha/beta counter. The average (range) activity concentrations of gross alpha and gross beta were determined as 105 (20-495) mBqL(-1) and 195 (70-850) mBqL(-1), respectively. Average annual effective dose to adults caused by ingestion of water samples was estimated as 74.1 +/- 43.2 mu Sv y(-1). The average estimated cancer risk value depending on irradiations was calculated as 3.8 x 10(-4) and 2.6 x 10(-4) for the region using the nominal probability coefficients recommended by ICRP 60 and ICRP 103, respectively. Annual effective dose values in 10.4% of samples exceeded the limit values suggested by WHO for drinking waters in terms of beta activity and this was 0.8% for alpha activity. Moreover, contribution of K-40 to the gross beta activity in drinking waters of the region was determined as 47%.