Background: Children within historically disadvantaged non-Western South African communities are considered as particularly vulnerable to the development of anxiety problems. Although the need for accessible mental health interventions is evident, this need has remained unmet in a country with extreme socio-economic disparities and a lack of mental health resources. Cognitive behavioural therapy-based (CBT-based) interventions that employ brief and intensive delivery methods may overcome existing barriers to access to mental health services faced by many South African children and may ameliorate the burden placed on under-resourced mental health care services. Aim: To provide preliminary evidence on the effectiveness of a brief, intensive CBT-based anxiety prevention intervention conducted in a South African context. Method: A mixed-methods approach, with quantitative and qualitative data, was used to evaluate the effects of the CBT-based programme in a sample of 21 farmworkers' children aged 9-14 years living in disadvantaged semi-rural communities of the Western Cape. A quasi-experimental design with an immediate intervention (experimental) group and a delayed intervention (control) group was applied in the quantitative component of the study. The qualitative component was based on focus group data. Results: In general, positive effects were noted for the CBT-based anxiety prevention programme in these vulnerable children. Quantitative data revealed a trend reflecting a reduction of self-reported anxiety levels. Qualitative support for the acquisition and application of the CBT-based programme skills was also found. Conclusion: This pilot study indicates that a brief, intensive CBT-based prevention programme holds promise for the effective reduction of anxiety in vulnerable South African children.