General internal medicine (GIM) is a communicatively complex specialty because of its diverse patient population and the number and diversity of health care providers working on a medicine ward. Effective interprofessional communication in such information-intensive environments is critical to achieving optimal patient care. Few empirical studies have explored the ways in which health professionals exchange patient information and the implications of their chosen communication forms. In this article, we report on an ethnographic study of health professionals' communication in two GIM wards through the lens of communication genre theory. We categorize and explore communication in GIM into two genre sets-synchronous and asynchronous-and analyze the relationship between them. Our findings reveal an essential relationship between synchronous and asynchronous modes of communication that has implications for the effectiveness of interprofessional collaboration in this and similar health care settings, and is intended to inform efforts to overcome existing interprofessional communication barriers.