BACKGROUND AND AIMS Continuous audit of clinical practice is an essential part of making improvements in medicine and enhancing patient care. Validated tools are needed to gather evidence for comparisons. Recently, Physiological and Operative Severity Score for the enumeration of Mortality and morbidity (POSSUM) and Portsmouth-POSSUM (P-POSSUM) scores were evaluated in Indian patients undergoing elective craniotomy and it was concluded that P-POSSUM was highly accurate in predicting overall mortality. We wished to study whether this system could be used in a different country and health care system [United Kingdom, UK]. We have evaluated these scores in patients undergoing elective and emergency craniotomies in a tertiary centre in the UK. METHODS Data was collected from all neurosurgical patients who underwent craniotomy overone year. Preoperative variables were collected prior to induction of anaesthesia, and operative variables were also collected. Chi-square test was used for expected and actual mortality differences. Survivor and non-survivor demographics were compared by one-way ANOVA for continuous and Chi-square for categorical variables. RESULTS One hundred and forty-five patients were studied. Mean [SD] physiologic score of the patients was 18.83 [5.07], and mean [SD] operative score was 18.09 [3.75]. P-POSSUM was a better predictor for elective patients and for those undergoing immediate life-saving surgery. CONCLUSION This study confirms and validates the findings of previous work that P-POSSUM is an accurate and reliable tool for estimating in-hospital mortality. It also confirms its usefulness in comparison of results across healthcare systems internationally. Larger scale evaluations may be needed to examine its usefulness in emergency procedures.