Uzulmez underground coal mine, one of 5 collieries in Zonguldak bituminous coal basin, is located on the West Black Sea region in Turkey. The radioactivity of the terrestrial natural radionuclides (226)Ra, (232)Th and (40)K in rock and coal samples from 17 different locations in the mine were measured by using gamma spectrometry to determine the radiological implication of the mine. The highest radioactivity concentrations for (226)Ra, (232)Th and and (40)K were found to be 118.8. 49.1. 561.7 Bq kg(-1) and 127.7. 145.3, 1125.9 Bq kg(-1), in coal and rock samples, respectively. The radium equivalent activity, the internal hazard index and the annual dose equivalent associated with the radionuclides were calculated to assess the radiological hazard of natural radioactivity in the samples, and compared with the international recommended values. The measured activity concentrations were also compared with those from other countries in the world. The results show that radiological effects of natural radionuclides emanated from rock and coal are negligible for this mine.