OBJECTIVES: The objectives were, first, to determine whether adherence to malaria prophylaxis could be predicted by (i) health beliefs specified by the Health Belief Model and the Theory of Planned Behaviour, and (ii) communication during the consultation in a travel clinic; and secondly, to examine the impact of the consultation in changing travellers' health beliefs. DESIGN: A prospective study using regression analysis. METHODS: The participants were 130 consecutive travellers attending a travel medicine clinic. Health beliefs were measured pre- and post-consultation. The consultations were coded from audiotape using the Roter Interaction Analysis System and a content analysis method recording discussion about malaria and prophylaxis. Adherence was assessed by a follow-up telephone interview. RESULTS: Perceived susceptibility to malaria, perceived benefits of medication and intentions to adhere increased significantly as a result of the consultation, and the perceived permanent nature of side effects reduced significantly. At follow-up (N = 107), 62% reported full adherence, 25% partial adherence and 12% poor/no adherence. A multinomial logistic regression analysis revealed that perceived benefits of medication, length of stay, health professional discussion about adherence and travellers' questions and statements independently predicted reported adherence. CONCLUSIONS: Health beliefs and communication significantly predicted adherence in this setting. The findings also suggested qualitative differences between travellers who adhered fully, partially or poorly. Although the clinic consultation had a positive impact, emphasizing benefits of medication and resolving potential barriers to adherence could improve adherence in the population.