Introduction: Diabetes mellitus (DM) refers to a group of common metabolic disorders that share the phenotype of hyperglycemia. World health organization in 2011 report estimates that more than 346 million people worldwide have DM. There are essential self-care behaviors in people with diabetes which predict good outcome namely healthy eating, exercise, monitoring of blood sugar, compliant with medication. The aim of this study is to assess self-care practice among diabetic patients in Hosanna Nigist Elenni Mohammed Memorial Hospital. Method: A descriptive institutional based cross sectional study design was used by convenient sampling technique and the data was collected using interviewer administered structured questionnaires, from December 9-June 10, 2016. Results: A total of 165 respondent were included in the study; while majority 95(58.6%) male and in the age group of 18-60 years 128(79.0%). Significant number of client sometimes adhere to healthful diet 65(40.1%); almost all 151(93.2%) not adhere to SMBG; 47(29%) were not adhere to physical activity that exactly meet the recommended guideline; 60.5% of client were not adhered to foot care and 110(68%) where not adhere to medication recommendation for DM patients. Conclusion: finding of this study were indicated that most of patients had no adherence to most of self-care practice especially in foot care and Self Monitoring of serum glucose. Generally, adherence to self-care practice was suboptimal among adult diabetic patients in Hosanna Nigist Elleni Mohammed Memorial Hospital diabetic clinic. The hospital administration should establish a specialized DM clinic so that follow-up and education service should be integrated with both treatment and education.