In this study, antioxidant, antiacetylcholinesterase, anti-inflammatory, and DNA protecting activities of the aerial parts of Glaucium grandiflorum var. grandiflorum were evaluated. The lyophilized methanolic extract of the aerial parts of G. grandiflorum var. grandiflorum was investigated for potential in-vitro antioxidant properties in thiobarbituric acid test using the lipid peroxidation of liposomes, ferric ion reducing antioxidant power (FRAP), 1,1-diphenyl-2- picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonate) free-radicals and hypochlorous acid scavenging assays. The extract demonstrated antioxidant activity in all the assays. The (AChE) inhibition capacity of the lyophilized methanolic extract at 320 mu g/mL (80.75 +/- 1.59%) was found to be strong and almost equal to the inhibition capacity of the positive control, galantamine (82.23 +/- 2.21%) at 25 mu g/mL. The significant AChE inhibitory activity suggests that the extract may be beneficial in the treatment of Alzheimer's disease. The extract also showed inhibitory activity against plasmid DNA damage (94%), as well as COX-2 69.05%, which is a target for many anti-inflammatory and cancer-preventive drugs. These results indicate that G. grandiflorum var. grandiflorum methanolic extract is an excellent source of compounds with antioxidant, anti-acetylcholinesterase and anti-inflammatory properties that prevent DNA damage.