[en] The natural background radiation in Zhejiang Province was measured and the dose to population was estimated. The results showed that the population-weighted average values of the absorbed dose rate in air from cosmic ray ionization were 3.0 x 10^-8 Gy·h^-1 outdoors and 2.7 x 10^-8 Gy·h^-1 indoors. The average absorbed dose rates in air from terrestrial γ-radiation were 9.1 x 10^-8 Gy·h^-1 outdoors and 14.9 x 10^-8 Gy·h^-1 indoors. The average values of radon in air were 17.2 Bq·^-3 indoors and 12.7 Bq·m^-8 outdoors. The contents of natural radionuclides in food and water were measured. The total annual individual average effective dose from natural background radiation was about 2.0 mSv. The contributions of cosmic rays, terrestrial radiation radon and thoron daughters exposure in air and internal exposure within the body were about 0.24, 0.77, 0.67 and 0.35 mSv, respectively. The annual collective effective dose to population in the province was estimated to be 8.5 x 10⁴ man Sv·a^-1