OBJECTIVES: Reducing readmissions is a National Health Service (NHS) Key Performance Indicator.  Ambulatory care units may provide financial savings, but high quality and effective service delivery is dependent on having an understanding of an individual hospital's admissions.  Comparison of patients with single or multiple comorbidities on admission or in other words multiple admission diagnoses, may help plan and deliver appropriate health care and support services in the most appropriate setting. We compared patients with multiple admission diagnoses to patients with one single admission diagnosis, to investigate whether there are differences in patient demographics, length of stay and readmission. METHODS: We conducted a retrospective audit of all non-elective adult acute medical admissions over a 6 week period. We collected information on patient demographics, ICD-10 diagnosis and length of hospital stay. We reviewed all electronic discharge summaries and grouped admissions according to ICD-10 classification.  We matched patients with multiple diagnoses to patients with similar ICD-10 diagnosis, without other co-morbidities. The length of stay, and readmission rates were also recorded and compared. RESULTS: A total of 863 admissions were analysed. We matched 41 patients with multiple co-morbidities and same admission diagnoses to patients discharged with a comparable single ICD-10 diagnosis.  Both groups had similar female to male ratio.  The mean age in both groups was 65 (p=0.42).  However, the length of stay was statistically significant (p=0.002) between the two groups (multiple diagnosis 12 days vs 6 days for single diagnosis).  Moreover, patients with multiple admission diagnoses had higher readmission rates within a week and a month (0 patients with single admission diagnosis vs 5 patients with multiple admission diagnoses).  CONCLUSIONS: Both groups had similar demographics, but co-morbidities can lead to longer hospital stay, and increase risk of hospital readmission.  Patients with multiple co-morbidities should have more detailed discharged planning by multidisciplinary team. Patients without multiple co-morbidites can be safely managed in an ambulatory care setting.