The clinical value of routinely obtained postoperative chest radiographs (CXRs) in post-anaesthesia care unit (PACU) patients is largely unknown. To determine the diagnostic efficacy and treatment impact of postoperative routinely obtained CXRs in a university hospital PACU. Observational study collecting the expectations of attending physicians, the findings on routinely obtained CXRs and actions based on the findings on these CXRs in postoperative PACU patients. A 22-bed PACU in a university hospital in the Netherlands. Patients admitted to the PACU during a 9-month period. The analysis was restricted to CXRs routinely obtained during the first PACU admission, i.e., CXRs obtained during later admissions were excluded. Diagnostic efficacy, defined as the percentage of CXRs showing any unexpected major abnormality; treatment impact, defined as the percentage of CXRs showing an unexpected major abnormality that triggered a predefined change in therapy. The analysis included 294 postoperative CXRs. Of them 94 showed a new and unexpected predefined major abnormality (diagnostic efficacy of 35%). Of these 94 CXRs, only 10 triggered an intervention (treatment impact of 4%). The diagnostic efficacy of routinely obtained postoperative CXRs in PACU patients is fair; the treatment impact seems low if we assume that all CXRs that showed an abnormality but were not followed by an intervention and did not require an intervention. Future research should focus on the safety and cost-effectiveness of abrogating routine postoperative CXRs.