Augmentative and alternative communication (AAC) strategies benefit learners with complex communication needs (CCN) by allowing them to participate, interact and learn. AAC is realised in the South African Education policy; however, research indicates that many teachers still have limited AAC knowledge. With this study we aimed to describe the effect of a newly developed evidence-based AAC training programme on special school teachers' perceptions of their own abilities related to teaching learners with CCN as well as their perceptions of the general academic, communication, and classroom interaction skills of learners with CCN and finally the teachers' perceptions of the inclusion of learners with CCN. A quasi-experimental pre-test-post-test group design with a non-randomised control group was used, employing a standardised measuring instrument, with 5 subscales, namely the modified teachers attitude scale (MTAS). The sample size included 58 teachers who participated: 6 in the pilot, 34 in the experimental and 18 in the control group. The brief AAC training session of 4 hours had a positive, statistically significant effect on several items on the subscales measuring teachers' perceptions of their abilities related to teaching learners with CCN, as well as their perceptions of the communication of learners with CCN, classroom interaction skills, and teachers' perceptions on the inclusion of learners with CCN. AAC training is recommended for special school teachers to enhance their own knowledge and to enhance the academic and social skills of learners with CCN. Furthermore, future studies are recommended to determine the prevalence of learners with CCN to influence the planning of services for this population in this context.