The aim of the present study is to examine the impact of an INSET programme on regular classroom teachers' attitudes towards deaf students educated in regular primary schools. In this research project, a quantitative research approach is used involving randomised allocation of subjects to groups, and a pre-test--post-test design. The sample for each group consisted of a random allocation of 61 teachers to an experimental group and 61 teachers to a control group. The research instruments were: 1) a programme of INSET courses based on the "Deaf Friendly Teaching: Practical Guidance for Teachers Working with Deaf Children" (National Deaf Children's Society, 2004), and 2) The Opinions Relative to Mainstreaming survey, which was developed by Antonak and Larrivee (1995), and was translated and adapted by Kircaali-Iftar (1997) in Turkey. The results indicated that the teachers in the experimental group increased their knowledge about deafness and that their attitudes were significantly more positive. In particular, the teachers' attitudes changed in relation to classroom management and knowledge about the education of deaf students in inclusive settings. (Contains 4 tables.)