Purpose: To study the role of C-reactive protein (CRP) in the progression of diabetic retinopathy before and after treatment to determine if it can be used as a biomarker for progression or regression. Methods: This observational case study included 90 persons divided into 4 groups: group A of 30 normal persons (non diabetic) as a control group, group B of 30 diabetic patients without retinopathy, group C of 30 untreated patients with proliferative diabetic retinopathy (PDR) and group D of the same patients of group C after 3 months of laser treatment by pan retinal photocoagulation (PRP). Serum CRP protein was measured in all groups, interpretation of results was applied. Results: The study revealed that serum CRP level increased significantly in patients with PDR (group C) in comparison to both groups of normal control persons (group A) and diabetic patients without retinopathy (group B) (P 0.05). Also the same finding was noticed in elderly patients above 50 years. Conclusion: CRP is considered a biomarker for PDR even in older age patients, but not a good indictor used for follow up patients after treatment.