Many anti-bullying programmes use teachers in the critical role of provider, yet few trials focus on enhancing their ability to fulfil this role. As teachers' readiness may impact on the effectiveness of anti-bullying programmes, the aim of this study was to evaluate an awareness programme for primary school teachers in Dhaka, Bangladesh. A 2 (group) x 3 (time) Cluster Randomised Controlled Trial was conducted sampling six clusters (3 control with 56 teachers, 3 intervention with 60 teachers). Four 2-h sessions were conducted weekly. Effectiveness was measured using questionnaires at pre-test (1 week pre-programme), post-test (1week post-programme) and follow-up (4 months later). They assessed the definition of and perceptions of bullying, intentions to act and actions taken against bullying. All constructs except the latter improved significantly for the intervention group relative to the control group. It is argued that bullying policies should be introduced that include regular in-service teacher training.