Objectives: This study evaluated the effects of reading different versions of a fotonovela about diabetes in resource-poor settings in South Africa. Design: An experimental study was conducted with 411 participants, comparing a fotonovela with a younger protagonist, a similar fotonovela version with an older protagonist and a no message control condition. Differences between the two fotonovela versions were analysed for two age groups of readers (25-49 years, and 50 years and older). Setting: Community centres in vulnerable communities in the South African provinces of the Western Cape, the Northern Cape and Gauteng. Method: In the experimental conditions, participants completed a questionnaire after reading one of the fotonovela versions. Participants in the control condition answered similar questions without having read a fotonovela. Results: Both fotonovela versions resulted in more diabetes knowledge than the control condition. Limited positive effects were found for attitudes and behavioural intentions. In the younger participant group, age similarity between the protagonist and readers resulted in knowledge gain, while in the older participant group, no such effect was found. In both age groups, no age similarity effects were found for attitudes or behavioural intentions. Conclusion: This study confirms that fotonovelas can be an effective means of health communication. Furthermore, for a narrative on a health topic for which age is relevant, it can be beneficial to choose a young protagonist. For readers from the same age group, the impact of the story on knowledge acquisition may then be greatest, while for older readers, the age of the protagonist does not seem to influence the knowledge effects of the story.