An original study about beliefs, conceptions and discourse analyses of organic chemistry teachers is presented. We used Likert questionnaires and discourse analysis to examine conceptions of the nature of science, learning and teaching at university level. A case study of four female teachers with varying experience and teacher training was performed. The results show that when teachers were asked about their beliefs, they tended to express constructivist ideas, especially about the nature of science. However, in their practical discourse, during the classes, they exhibited more traditional positions. The discourse analyses then become a powerful tool which can be considered a beliefsgate to analyse conceptions. (Contains 2 notes, 5 tables, and 2 figures.)