Background <p>Patients’ and relatives’ feedback is used by hospitals to improve the quality and safety of care. It can be solicited, as in the case of satisfaction questionnaires or complaints collected by mediation centers. Hospital users also provide unsolicited feedback by writing compliment letters, which are generally considered as expressions of gratitude. This study investigated compliment letters received by a neonatology service from parents with a twofold objective: first, to investigate compliment letters’ content regarding parents’ experiences and second, to explore underlying needs that motivated parents to provide feedback.</p> Methods <p>This qualitative descriptive study was based on the analysis of 573 compliment letters collected by the neonatology service of Lausanne University Hospital in Switzerland between 2009 and 2020. The parents’ lived experiences contained in compliment letters were analyzed using framework analysis. The needs and functions that their feedback fulfilled were examined through a custom analysis method, combining psychological and socio-anthropological perspectives, and informed by the results of the framework analysis.</p> Results <p>Five core themes characterized parents’ experiences: recall of the care and hospital stay (contextual information to refer to the children’s stays in the service), life after the hospital discharge (children’s health evolution and development), parents’ feelings (how parents experienced their children’s care), perception of the healthcare professionals (healthcare professionals ways of being and doing), parents’ gratitude (thanks to healthcare professionals for their acts or their qualities). Five underlying needs were identified: thanking the team, closure (claim that the children were no longer patients), partial closure (feedback on the state of the children), taking its own place in the care (parent’s account of the impact of children’s hospitalization), managing the sense of indebtedness (parents’ acknowledgement that they owe something to the team).</p> Conclusion <p>When parents write compliment letters, they mostly express how they experienced their children’s hospitalization and how they managed to make sense out of it. Compliment letters thus have other functions than expressing gratitude. They allow parents to sustain relationships with healthcare professionals, support the normalization of their children’s situation and their recovery or provide testimony of experiences. They contain important information about the writers, health care professionals, the relationship they have established, hospital operations and healthcare organization. As hospital users' experiences are thought to contribute to health care quality, it matters that health services consider the information they convey.</p>