The purpose of the present study was to examine primary school teachers’ epistemological beliefs and teaching efficacy beliefs about mathematics and the relationship between these two constructs. Two paper and pencil questionnaires were administered to 184 in-service and pre-service teachers. Exploratory factor analysis yielded five epistemological factors that were labelled: simplicity of knowledge, certainty of knowledge, innate ability, source of knowledge, and speed of learning. Participants in general stated quite efficacious to teach mathematics. The regression analysis showed that epistemological beliefs predict teaching efficacy beliefs and vice versa. Implications of these findings concerning the teaching and learning process are discussed.