Background Trust is an essential phenomenon of relationship between patients and healthcare professionals and can be described as an accepted vulnerability to the power of another person over something that one cares about in virtue of goodwill toward the trustor. This characterization of interpersonal trust appears to be adequate for patients suffering from chronic illness. Trust is especially important in the context of chronic cardiovascular diseases as one of the main global health problems. Research Aim The purpose of the qualitative (...) study was to gain a deeper understanding of how people with chronic cardiovascular disease experience and make sense of trust in healthcare professionals. Research Design Eleven semi-structured interviews with participants analysed using interpretative phenomenological analysis to explore in detail their lived experience of trust as a relational phenomenon. Participants and Research Context Participants with chronic cardiovascular disease were purposively recruited from inpatients on the cardiology ward of the university hospital located in central Slovakia. Ethical Considerations The study was approved by the faculty ethics committee. Participants gave their written informed consent. Findings Four Interrelated Group Experiential Themes Sense of co-existence; Belief in competence; Will to help; Ontological security with eight subthemes were identified. The findings describe the participants' experience with trust in healthcare professionals as a phenomenon of close co-existence, which is rooted in the participants’ vulnerability and dependence on the goodwill and competence of health professionals to help with the consequence of (re)establishing a sense of ontological security in the situation of chronic illness. Conclusion Findings will contribute to an in-depth understanding of trust as an existential dimension of human co-existence and an ethical requirement of healthcare practice, inspire patient empowerment interventions, support adherence to treatment, and person-centred care. (shrink)