Purpose: To identify correlation between severity of diabetic macular edema (DME) detected by OCT, and severity of diabetic retinopathy (DR) detected by FFA. Methods: Retrospective review of OCT and FFA performed for 25 eyes of 20 Patients with DR and DME. Using this information patients were categorized into groups; according to angiographycaly detected severity of DR: Group A: mild NPDR (7 eyes) Group B: moderate NPDR (10 eyes) Group C: severe NPDR (2 eyes) Group D: PDR (6 eyes) Results: In Group A: thickening with homogeneous optical reflectivity was detected in 4 eyes, thickening with decreased optical reflectivity in the outer retinal layer in 3 eyes, foveolar detachment without traction in 1 eye. CMT was < 300 in 2. Eyes, 300-500 in 1 eye, and > 500 in 2 eyes In Group B: thickening with homogeneous optical reflectivity was detected in 6 eyes, thickening with decreased optical reflectivity in the outer retinal layer in 4 eyes, foveolar detachment without traction in 2 eyes. CMT was < 300 in 1.eye, 300-500 in 7 eyes, and > 500 in 2 eyes In Group C: thickening with decreased optical reflectivity in the outer retinal layer in 2 eyes. CMT was 300-500 in 2 eyes. In Group D: thickening with homogeneous optical reflectivity was detected in 2 eyes, thickening with decreased optical reflectivity in the outer retinal layer in 4 eyes, foveolar detachment with apparent vitreofoveal traction in 2 eyes. CMT was 300-500 in 5 eyes, and > 500 in 1 eye. Conclusion: OCT revealed the possibility of the incidence of more severe DME than proportionate with angiographically detected severity of DR.