Aims and objectives: To investigate final-year nursing students' use of situation awareness when making clinical decisions about patients' progress postsurgery. Background: Making clinical decisions about patient care is a generic nursing competence, developed in preregistration nursing programmes and critical to providing safe patient care. Situation awareness is an important precursor to making decisions and is linked to improved clinical outcomes. However, there is evidence to suggest that nursing students feel inadequately prepared to make clinical decisions. Design: Endsley's (Situation awareness analysis and measurement. Hillsdale, NJ: Lawrence Erlbaum Associates, 2000) 3-level situation awareness framework was used to guide the study. Level 1 situation awareness is perception of information required to make a decision. Level 2 relates to comprehending the information. Level 3 situation awareness is projecting how this information will inform the future. Twelve final-year nursing students were recruited to participate. Think-aloud research method was used to capture students' decision-making, followed by semi-structured interviews. Data were analysed using an adapted protocol analysis and were encoded inductively. The COREQ checklist has been used in reporting the study. Results: Students demonstrated level 1, 2 and 3 situation awareness when making clinical decisions. However, it was not demonstrated consistently and at times subsequent decision-making was inappropriate. Three themes emerged: “systems approach to assessment of postoperative patients”; “policy drives practice”; and “deferring decisions to registered nurses”. Within the themes, students demonstrated differing levels of situation awareness. Conclusion: Making safe clinical decisions is a paramount skill for nurses; however, student nurses are ill-equipped to undertake this skill. Situation awareness is important in informing safe decision-making, but students' use of situation awareness is variable. Cognitive apprenticeship, applied to supporting development of situation awareness, affords the opportunity to develop students' decision-making. Relevance to clinical practice: Clinical decision-making is a generic competence for all registered nurses and imperative for safe practice. However, student nurses are unprepared to undertake this skill once registered.