Background: The prevalence of Diabetic Retinopathy (DR) in the world was estimated to be 100,8 million cases in 2010 and154,9 million cases in 2030. In 2007 - 2012, the prevalence of DR in Prof. Dr. Margono Soekarjo General Hospital ofPurwokerto was known 102 cases. Strict control glucose level and blood pressure by diet, physical activity, medicines, andstress management was needed to prevent DR complications. Under-go routine eye examination was same need to preventDR complications. To produces behavior in preventing DR complication should be needed several factors, such as knowledge and social support.Objective: To identify the relationship between knowledge and social support with preventing behavior of DR complication inDiabetic Clinic Prof. Dr. Margono Soekarjo General Hospital of Purwokerto.Method :This was a Cross-sectional approach-based on Correlational research. The populations involved 283 diabetic patients who had checked at a last month and not been being DR complication in Diabetic Clinic Prof. Dr. Margono Soekarjo GeneralHospital of Purwokerto. Samples were recruited based on incidental sampling involving 74 respondents. Data were collected through questionnaires. Bivariat analysis through Chi Square Test was data analysis technique used to test hypotesis.Results: The result between knowledge with preventing behavior of DR complication showed that there was signifcantrelationship, with p-value = 0,000. The corelation test result between social support with preventing behavior of DRcomplication showed that there was signifcant relationship, with p-value = 0,004.Conclusion: Based on the research, it was concluded that there was relationship between knowledge and social support withpreventing behavior of DR Complication in Diabetic Clinic Prof. Dr. Margono Soekarjo General Hospital of Purwokerto.According to the research results, it is recommanded to nurses and the other health practitioners to keep and improve healthcare to diabetic patients and their family with health education.Keywords : Diabetes Mellitus, Diabetic Retinopathy, Knowledge, Social Support, Behavior