The study aims to determine pre-service science teachers' epistemological beliefs. For this purpose, five fourth grade pre-service science teachers enrolled at the education Faculty of a University in Kayseri participated in the research. Phenomenology design was used and a semi-structured interview including 13 items was conducted. The data were analysed through content analysis by developing codes and themes based on five epistemological belief categories. According to the findings, the participants' epistemological belief categories can be put in order from the most sophisticated to the most naive as follows: 'Omniscient authority', 'Certain knowledge and quick learning', 'Simple knowledge' and 'Innate ability'. The findings indicated that epistemological beliefs of the participants are at different development levels for each category. Since they reflect the individual differences, epistemological beliefs should not be ignored in developing a program and determining classroom activities.