The Theory of Planned Behaviour (TPB) assumes the possibility of predicting and explaining humans’ behaviour by identifying their intentions. The intentions are shaped by three groups of factors: attitudes towards, social norms and perceived behavioural control over the behaviour. The aim of the research is to examine the applicability of the TPB in medical tourism and to check whether there are differences in predicting the intentions of medical tourists from different countries. The study covered potential medical tourists—521 young consumers from three regionally important markets in medical tourism services: Jordan, Poland and Turkey. The study used a research survey to collect data, which were analysed using the multiple regression and analysis of variance methods. The research showed that the TPB model can be used in medical tourism. The results also show that the consumers’ country of origin is a significant factor when predicting their intention to use medical tourism services.