Purpose: The study aimed at evaluation of the role of ceruloplasmin (A protein involved in iron homeostasis and can inactivate free radicals) and other oxidative stress markers as superoxide dismutase (SOD), malondialdehyde (MDA) and catalase activity (CAT) in primary open angle glaucoma (POAG). Methods: This observational case control study included 90 persons divided into 3 equal groups: group A of 30 normal persons as a control group, group B of 30 patients of untreated (POAG) (firstly diagnosed) by the clinical characters including measuring intraocular pressure (IOP), optic disc cupping and visual field changes and group C of 30 patients of POAG under medical treatment by topical anti-glaucomatous drugs. Serum ceruloplasmin, superoxide dismutase, malondialdehyde and catalase activity were measured in all groups, statistical analysis of the data was performed. Results: In a comparison to group A of control, serum ceruloplasmin decreased significantly in group B of untreated POAG (20.95 ± 6.01) mg-dl and in group C of POAG under treatment (22.15 ± 6.14) mg-dl (P < 0.001), and there was no statistically difference between group B and C (P > 0.05). Also, serum superoxide dismutase increased significantly in group B (2.23 ± 0.4) and in group C (2.19 ± 0.38) U-ml (P < 0.001), and there was no statistically difference between group B and C (P > 0.05). Serum malondialdehyde increased significantly in group B (3.82 ± 0.74) nmol-ml and in group C (3.55 ± 0.73) nmol-ml (P < 0.001) in a comparison to the control group A (2.23 ± 0.41) nmol-ml, and there was no statistically difference between group B and C (P > 0.05). Serum catalase decreased significantly in group B (17.97 ± 2.75) U-ml and in group C (18.75 ± 2.33) U-ml in a comparison to the control group A (22.67 ± 3.05) U-ml (P < 0.001), and there was no statistically difference between group B and C (P > 0.05). Conclusions: Serum ceruloplasmin level and the antioxidant (CAT) activity significantly decreased, while serum levels of SOD, MDA significantly increased in cases of POAG. This may indicate the need for addition of anti-oxidative stress therapy in combination with the anti-glaucomatous drugs. Monitoring these markers can be considered good indicators for determination of the oxidative stress condition in such cases.