Relationships between subsidiary managers and headquarters (HQ) have been investigated through various research methods in the international management field. The diary method is an experience-based research method that helps to tap into the actions, reactions, and emotions of managers working in the international domain. To our knowledge, no study has shed light on subsidiary-headquarters relations using insights from subsidiary managers’ diaries. We introduce the diary method to international management research and present an illustrative study on subsidiary-HQ relations, based on diaries written by fourteen subsidiary managers. We note that subsidiary managers display multiple types of emotions when dealing with their corporate HQ. We discuss how the diary method can enrich international management research, and in particular studies on multi-level subsidiary-HQ relations. Based on our illustrative study, we propose guidelines for using the diary method in the international management field by providing insights into the diary study preparation, the collection of diary data, and data analysis.