Objective This study aimed to understand how different communication strategies influence patients’ behaviour in paying unpaid hospital bills. The research focused on a healthcare system where patients have to pay a significant portion of their medical costs out-of-pocket. Methods The research was conducted in collaboration with a debt collection agency in Latvia. The field experiment involved 9196 individuals with unpaid hospital bills. These individuals received randomly assigned reminders through mobile text messages and e-mails. The study compared the effectiveness of personalized messages, which included the recipient's name, with generic reminders and messages that appealed to social norms or public good contributions. Results The findings revealed that personalized messages, specifically those that included the recipient's name, significantly improved payment rates compared with generic reminders. Conversely, messages that used social norms or public good appeals did not have a significant impact on payment rates. Conclusions The study highlights the importance of personalized communication strategies in improving hospital debt collection. Even simple, cost-effective modifications in communication, like adding the recipient's name, can significantly enhance payment compliance. This approach not only keep the financial books of healthcare providers balanced but also suggests that personalized strategies can be extended to other areas of healthcare management. However, while these findings are promising, they indicate that more personalized and nuanced communication strategies are needed to address the broader issue of unpaid hospital bills effectively.