Contemporary educational reforms, both in the fields of science and mathematics, highlight the importance of pre-service teachers' preparation with regard to several meaningful standards. However, teachers' own self-confidence in science and mathematics teaching are likely to influence their efforts. Framed within a growing body of research focusing on pre-service teachers' efficacy beliefs in science and mathematics teaching, the present study attempts to investigate Greek pre-service primary teachers' efficacy beliefs in science and mathematics teaching; and further examine whether there is a relationship between the two. Participants comprised 171 pre-service primary teachers, who were in their second (n = 55), third (n = 64) or fourth year (n = 52) of study and the majority were female (n = 148). Pre-service teachers were asked to complete a questionnaire consisting of the Science Teaching Efficacy Belief Instrument - Form B (STEBI-B) and the Mathematics Teaching Efficacy Belief Instrument (MTEBI). Principal component analyses and reliability analyses were performed for both instruments to examine their adaptation into Greek. According to the results, preservice teachers had medium to high scores in the personal efficacy and outcome expectancy scales, for both science and mathematics teaching. Minor differences in pre-service teachers' scores were detected according to their year of study. Furthermore, pre-service teachers' efficacy beliefs in science were strongly correlated with their efficacy beliefs in mathematics. In general, although pre-service teachers appeared to be confident and well-prepared to teach science and mathematics in classrooms, more effort is required to put the international education reform standards into practice.