Objectives: to analyze hand hygiene determinants of informal caregivers in a hospital environment. Methods: qualitative study conducted with 55 caregivers at a university hospital in the Northeast of Brazil. A semi-structured instrument was used, adapted from Nola Pender's Health Promotion Model, from which the deductive categories were derived. Results: the general behavior included hand hygiene before meals and after using the bathroom. Sensitivity to the requirements for hand hygiene was observed, but the barriers and self-efficacy consisted of the availability of soap or alcohol-based hand sanitizers, the lack of knowledge on the importance of and forgetfulness of the practice. The reinforcement on the importance of the practice and being in a contaminated environment were influencers, and commitment, warnings, and training were indispensable. Conclusions: benefits related to protection from infections were seen as positive determinants for hand hygiene adherence. For non-adherence, factors such as lack of sanitizing supplies, ignorance towards the importance of the activity, and forgetfulness stood out.