Objectives: To describe morbidity and multimorbidity patterns among adults readmitted to an Australian regional health service, in terms of occurrence of the same and different morbidities at index admission and readmission. Methods: This cohort study used hospital admissions data for patients admitted between 1 July 2014 and 30 June 2016 to estimate proportions of unplanned readmissions (‘early’ within 30 days and ‘late’ within 1–6 months) with the same and different morbidities as the index admission. Readmission rates were estimated by selected sociodemographic, admission and diagnostic characteristics. Results: The majority of early and late readmissions were in different diagnostic groups and for different primary morbidities to the index admission. Only 38.8% of readmissions were in the same major diagnostic group as the index admission and 18.4% in the same Adjacent Diagnosis-Related Group. Twenty one percent of admitted patients were readmitted within six months, with this increasing to 35.3% among multimorbid patients. Conclusion: With increasing prevalence of multimorbidity, particularly among those at increased risk of readmission, it is essential to step away from a single disease focus in the design of both hospital avoidance and chronic disease management programmes. Holistic interventions and strategies that address multiple chronic conditions are required.