This study was aimed at describing disease patterns in a rural zone of Oromiya region, Ethiopia through a retrospective analysis of discharge records for 22,377 inpatients of St. Luke Hospital, Wolisso, Ethiopia in the period 2005-2007. The leading cause of admission was childbirth, followed by injuries, malaria and pneumonia. Injuries were the leading cause of in-hospital deaths, followed by pneumonia, malaria, cardiovascular disease and AIDS. Vulnerable groups (infants, children and women) accounted for 73.3% of admissions. Most of the disease burden resulted from infectious diseases, the occurrence of which could be dramatically reduced by cost-effective preventive and curative interventions. Furthermore, a double burden of disease is already emerging at the early stage of the epidemiological transition, with a mix of persistent, emerging and re-emerging infectious diseases and increasing prevalence of chronic conditions and injuries. This will lead to fundamental changes in the volume and composition of demand for healthcare, with a more complex case mix and more costly service utilization patterns. The challenge is to address the double burden of disease, while focusing on poverty-related conditions and targeting vulnerable groups. Monitoring disease and service utilization patterns through routine hospital information systems can provide sustainable, low-cost support for evidence-based health practice.