OBJECTIVES: Older patients represent those at greatest risk of adverse drug reactions (ADR) and potentially inappropriate prescribing (PIP). Therefore, they also represent the greatest opportunity for pharmacotherapy optimisation. Examining prescribing patterns is a key step towards identifying areas in which prescribing can be improved.  METHODS: As part of the SENATOR project, prescribing data was collected on 464 older patients presenting at emergency departments with acute illness at sites across six EU countries. Patients were followed up at discharge and three months post-discharge, where possible. The prescribing data was analysed to compare prescribing across the six countries. As the STOPP/START screening tool organises criteria by physiological system, the prescribed medicines were classified accordingly.  RESULTS: In total 8666 medicines were recorded for the 464 patients. The overall percentages were as follows; cardiovascular indications 39.01% (n=3381), central nervous system indications 7.69% (n=666), endocrine disorders 6.91% (n=599), gastrointestinal indications 9.04% (n=783), musculoskeletal indications 4.3% (n=373), respiratory tract indications 11.97% (n=1037), urogenital indications 2.05% (n=178), no valid indication recorded 3.80% (n=329), other indications 15.23% (n=1320). Comparing prescribing across the six sites, cardiovascular indications remained the most common and showed the lowest relative standard deviation across the six sites (x ̅= 41.38%, SD = ±6.68, RSD =16.14%). Respiratory tract (x ̅=9.56%, SD=±6.24, RSD=65.27%) and musculoskeletal indications (x ̅=3.78%, SD=±2.35, RSD=62.17%) showed the greatest variation in prescribing across the six sites.  CONCLUSIONS: Prescribing for cardiovascular indications accounted for the highest percentage of medications at each individual site. It was also the most consistent, showing the lowest variation in percentages across all six sites. This supports the fact that cardiovascular criteria make up the largest section of the STOPP/START criteria. Prescribing for respiratory tract and musculoskeletal indications showed the highest level of variation across the six sites. This variation may be indicative of over-prescribing in some sites and under-prescribing in others.