The aim of this study is to examine the role of oxidative stress (OS) by measuring Malondialdehye (MDA) levels to test Lipid Peroxidation as a marker of oxidative stress in serum samples in toxic injuries resulting from exposure to anticholinesterase insecticides (organophosphates and carbamates) in greenhouse workers in the coastal region of Syria. The study population comprised two groups (the majority of males): greenhouse workers who prepare and spray pesticides (100 workers, aged 18-61) and Control group (not never handle pesticides, 50 subjects, aged 19-58). Malondialdehye (MDA) levels were measured using enzyme-linked immunosorbent assay (ELISA). There was a significant difference in MDA levels in greenhouse workers group compared to control group (P˂0.05). Therefore, MDA levels could be considered as a biomarker for oxidative stress in greenhouse workers exposed to anticholinesterase insecticides and might be a useful diagnostic aid and monitoring exposure in those workers as well as cholinesterase enzyme.