INTRODUCTION: Polypharmacy and inappropriate prescribing are associated with negative health outcomes in the elderly. Several prescribing tools have been developed to assess medication appropriateness. Explicit (criteria-based) tools often do not take into account patients' preferences and comorbidities, and have little room for individualised clinical judgement. METHODS: A cross-sectional observational study was conducted in 243 elderly patients admitted to the Geriatric Medicine service in a Singapore tertiary hospital over one month. We incorporated an implicit (judgement-based) tool developed by Scott et al into a mnemonic, 'S-I-R-E', to assess medication appropriateness: S = symptoms ('Have symptoms resolved?'), I = indication ('Is there a valid indication?'), R = risks ('Do risks outweigh benefits?') and E = end of life ('Is there short life expectancy limiting clinical benefit?'). RESULTS: Inappropriate prescribing was present in 27.6% of patients. The most common reason for inappropriateness of medications was lack of valid indication (62.2%), followed by high risk-benefit ratio (20.7%). The most common medications that lacked valid indication were supplements and proton pump inhibitors. Polypharmacy was found in 93% of patients and was significantly associated with inappropriate prescribing (p = 0.047). CONCLUSION Inappropriate prescribing and polpharmacy are highly prevalent in the hospitalised elderly. The 'S-I-R-E' mnemonic can be used as a memory aid and practical framework to guide appropriate prescribing in the elderly.