Introduction: Amidst the 2020 COVID-19 pandemic, frontline healthcare workers may be faced with a host of challenging decisions and decisional consequences made within the context of potential shortages in personal protective equipment (PPE), an unknown virus, and treatment uncertainty, which may briefly decree one treatment effective and later to be of harm. Such decisions may require healthcare workers to violate their own long-standing ethical beliefs and place healthcare workers at risk of feeling betrayed by institutions or individuals they expect to “have their back”. Together, these circumstances may place healthcare workers at risk for the development of moral injury (MI), the psychological distress associated with the perceived betrayals of one’s moral or ethical values or perceived transgressions (i.e., acts of commission or omission by oneself or others). MI has been the subject of increasing research interest, particularly among military members and Veterans. Despite growing interest in MI, the clinical correlates of MI remain poorly understood. The objective of the current study was to investigate the relations among MI, symptoms of posttraumatic stress disorder (PTSD), depression, anxiety, stress, and difficulties with emotion regulation (ER) in a sample of Canadian military members and Veterans. Method: The Moral Injury Events Scale was administered to Canadian military personnel and Veterans who were receiving treatment for trauma-related disorders. Clinical-grade assessments of symptoms of PTSD, depression, anxiety, stress, and difficulties with ER also were administered. Correlational analyses were used to assess the relation of moral injury to these clinical markers of illness. Results: Increased levels of MI were associated with heightened avoidance and with alterations in the mood and cognition symptom cluster of PTSD. The relation between MI and difficulties with ER trended towards significance. Discussion: As well as confirming the association between severity of MI and elevated levels of Cluster C (avoidance) and Cluster D (negative alterations in mood and cognition) symptoms of PTSD, this preliminary study also suggests the need for further study of the association between difficulties with emotion regulation and the development of MI. Relevant methods of prevention of MI across the various military and healthcare sectors involved in the response to the COVID-19 pandemic are discussed.