Aim: To investigate the diagnostic efficacy and clinical application value of plasma endothelin-1 for diabetic retinopathy using receiver operating characteristic (ROC) curve analysis. Methods: This was a prospective investigational study. Funduscopy and fundus fluorescein angiography were used as gold standards for the diagnosis of diabetic retinopathy. Plasma endothelin-1 was measured in 96 diabetic patients with retinopathy (the case group) and 144 diabetic patients without retinopathy (the control group). Enumerative data were listed in a fourfold table. The measurement data were analyzed by Student’s t test and evaluated by cross-table analysis and ROC curve analysis. Results: (1) The plasma endothelin-1 concentration was higher in the case group than the control group (p = 0.002 < 0.01). (2) If the plasma endothelin-1 level of 162 pg/ml was adopted as the threshold for clinical diagnosis of diabetic retinopathy, the diagnostic sensitivity was 71.2%, diagnostic specificity 58% and diagnostic accuracy 66%. The positive predictive value was 69.81% and the negative predictive value 59.46%, and the positive likelihood ratio was 1.69 and the negative likelihood ratio 0.50. (3) When plasma endothelin-1 was used as a diagnostic criterion for diabetic retinopathy, the area under the ROC curve was 0.737. Conclusions: Plasma endothelin-1 plays an important role in the development and progression of diabetic retinopathy. When 162 pg/ml of plasma endothelin-1 was adopted as the diagnostic threshold, the diagnostic accuracy was medium; hence, the plasma endothelin-1 level can be used as the first step for diabetic retinopathy screening.