This work presents the first book-length examination of Medical English as a Lingua Franca (MELF). It posits that MELF offers significant insights into English as a Lingua Franca (ELF) studies, which have historically focused on less critical communication scenarios. Medical contexts, by nature, require exceptional precision and urgency in communication. The authors draw on their research and existing studies to provide a nuanced perspective, contrasting with the often optimistic outlook on communicative success in general ELF research. The book introduces a theoretical framework for understanding how various elements of healthcare communication influence interactions among ELF speakers, thereby expanding the understanding of this specialized linguistic area.