Influenza is a contagious respiratory virus that causes high rates of morbidity and mortality and is associated with life-threatening complications. Despite the wide availability of a highly effective influenza vaccine, nurses are reluctant to receive influenza vaccination and vaccination rates among them are low. The purpose of this study was to generate a substantive theory/theoretical model regarding the phenomenon of influenza vaccination uptake by registered nurses (RNs). The study used grounded theory to develop a deeper understanding of RNs' decision-making regarding the acceptance or refusal to be vaccinated against influenza in Nova Scotia, Canada. Data were collected from 11 RNs using an unstructured and conversational interview format and analysed using the constant comparative method. The primary finding of this study is that nurses consider getting vaccinated to be a personal decision (the core variable). Their decisions are based on sources of information (including formal education, continuing education and the media); personal knowing (personal philosophy, perceived risks and benefits and personal experience); and personal modifiers (the availability and accessibility of the vaccine). The process of making a personal decision defined in this study provides a framework for creating more effective influenza immunization education and delivery programs.