Pedagogical beliefs and attitudes significantly determine the professional skills and practice of teachers. Many professional development programs for teachers aim to the elaboration of the pedagogical knowledge in order to improve teaching quality. This paper presents the study of pedagogical beliefs of computer science teachers in Greece. The research data reveal that computer science teachers usually hold mixed traditional and constructivist theories which are generally irrelevant to either demographic factors or their pedagogical training. In some cases statistically significant correlations to the educational level or the total teaching service are detected. The results of the study set out suggestions concerning the design of pedagogical training programs.