Psychotherapists believe they make rational choices about their theoretical orientation, the type of treatment offered to patients, and the type of "evidence" they will attend to, but there is little thought given to how thinking styles or epistemological biases affect these decisions. Cognitive-behaviour therapy and psychodynamic practitioners are particularly good examples of two orientations that appear to have two very different types of practice, ways of thinking about evidence, and theories of knowledge. The interactions between psychotherapeutic orientation and the gender and experience of therapists for the cognitive-epistemological traits revealed that gender made no difference but experience did. The research and study presented here will show how different patterns of cognitive style and epistemology are significant influencing factors in psychotherapists' choice of theoretical orientation and treatment modality. Attempts to integrate psychoanalysis with cognitive therapy without an awareness of their different epistemologies should be treated with extreme caution in order to avoid possible theoretical and methodological confusion.