Objective: This study was designed to identify the types of behavior displayed by head nurses that most often inspire trust among health workers and to determine what aspects of that behavior are most related to trust. Methods: The research was qualitative and involved 90 staff members at a highly complex public hospital in Chile: 26.7% were nurses and 73.3% were paramedic technicians. The critical incident technique was used to collect the data. An interpretative phenomenological analysis of semi-structured interviews yielded 66 critical incidents. Those interviewed were asked to describe a specific, meaningful incident they had experienced with their head nurses. Results: Four categories were identified: instrumental help with problems, emotional support, support and defense against attacks, and support for empowerment. All the categories correspond to the benevolent aspect of the perception of trust in head nurses. Conclusion: Trust in nursing leadership is facilitated when head nurses lead in a way that fosters trust based on a positive emotional bond with staff members. This is accomplished by demonstrating concern when staff members face difficulties, both at work and at home, and by providing emotional or professional support and assistance.