Conversational interactions contribute not only to the sharing of information and establishment of consensus but also to the construction and sustenance of mutual trust among conversational participants in our daily lives. The interrelationship between trust and conversational interactions has not been studied extensively in cognitive sci- ence. One reason for this lack of research is the fact that a study of social emotions such as trust requires real fields, since social emotions in their natural, non-artificial forms are not readily observable in laboratory settings. We introduce a notion of concern alignment to describe the surface conversational processes toward mutual trust forma- tion. Focusing on medical communications as our research field, we collected health guidance conversations between nurses and patients who were diagnosed as having metabolic syndrome, and we provide a qualitative analysis of the structure of conver- sations in terms of a set of dialogue acts we propose for the description of concern alignment processes. We demonstrate that the idea of concern alignment enables us to capture and elucidate both the local and the global structures of mutual trust formation in conversational consensus-building processes. We also discuss underlying mechanisms connecting concern alignment and mutual trust.