Evaluation of teaching by students at the university is a matter that has been given great emphasis internationally. A significant number of research studies explore possible sources of bias. Discussion of the likely evaluation of universities in Greece has focused attention on the subject, raising, at the same time, among others, issues which have not received much attention, such as, the issue of possible bias due to gender. Student evaluations of professors may be biased against women in subtle ways. Usually study finds that average rating of all male professors does not differ significantly from the average of all female professors, but most studies ignore the gender of the student who evaluate, the disciplines involved and the fact that female professors are often judged on a double standard. In this paper, after a literature review in order to examine possible sources of bias in the evaluation of teaching by students, special emphasis is given on the gender factor. The data used in this pilot study are obtained from an anonymous questionnaire administered to students as part of my seminar ''Gender and Education'' at the Department of Education at Aristotle University of Thessaloniki. It represents the first attempt to test any possible source of bias in the evaluation of teaching by students in Greece. We examined the impact of some student characteristics, such as gender and perceptions on the evaluation of teaching. The data demonstrate that when the gender of the rater and the professor is considered we find a more complex pattern than the above mentioned. Also, female professors appear to be evaluated according to different expectations due to stereotypes of gender roles - women faculty are still a minority -and these expectations affect student evaluations -stereotyped expectations of men coincide with what we expect of professors (the analysis of data has not finished yet). The effects of gender on student evaluations of professors are complex and should not be dismissed. Studies at a wider range of institutions will help us clarify how and when gender factors affect student evaluations, particularly teacher gender in interaction with student gender and the division. Finally, the consequences of a likely differentiated evaluation of female and male faculty members are discussed. Several outcomes may be useful for the design of teaching evaluation questionnaires at first in the Greek Universities and for interpretation of student rankings themselves. However, the results should be treated with caution. The main consideration is that no allowance is made for either instructor or subject-related characteristics.