Teachers contribute enormously to a positive social climate in science classes, particularly through their communication with students. In the study described in this article, a questionnaire [The Teacher Communication Behaviour Questionnaire (TCBQ)] developed by She and Fisher (2000) was used. TCBQ can be used to assess students' perceptions of science teachers' interpersonal communication behaviours in their classroom learning environments. TCBQ has five scales: Challenging, Encouragement and Praise, Non-Verbal Support, Understanding and Friendly, and Controlling. The TCBQ was used with a large sample of university students in Turkey. Girl students perceived more of these communication behaviours in their teachers than did the boy students. There were statistically significant differences (p less than 0.0001) on four of the five scales of the TCBQ between teachers' gender. Statistically significant differences were not found among different grade classes. Teachers in biological and chemistry science classrooms exhibited more favourable behaviour toward their students than did those in physical science classrooms. (Contains 4 tables.)