Purpose: Encountering patients with chest pain iscommon for Registered Nurses (RNs) in Emergency Medical Services (EMS) who are responsible for the patient’s medical and nursing care. From a lifeworld perspective, bodily illness is related to existential suffering, requiring knowledge to asses the situation from a holistic perspective. The aim of this study is to describe the caring approach when RNs encounter patients with chest pain. Methods: A phenomenological methodology to capture RNs’ lived experiences was chosen. Seven qualitative in-depth interviews were conducted at three ambulance stations in Sweden. Results: The essence of the caring approach while encountering patients with chest pain comprises two constituents; “trust based on confidence and competence” and “the collegial striving towards the best possible care”. Trust is two-parted; trust in oneself, and striving towards gaining the patient’s trust. Competence and experience when combined, develop into confidence especially in stressful situations. The caring approach is nurtured in a well-functioning collegial team. Conclusions: This study contributes to understanding the caring approach based on the specific patient’s lifeworld in holistic EMS care. By trusting oneself, the patient, and one’s colleague, RNs in EMS shift focus from medical-orientated care to a holistic lifeworld caring approach. More research is needed on trust as a phenomenon in EMS, both from caregivers’ and patients’ perspectives.