Organophosphate insecticides (OPI) poisoning remains a major cause of morbidity and mortality in the third world countries. The continuous use of these pesticides tends to leave residues of these pesticides in agricultural crops, which in turn may harm people. The present study aimed to investigate the pathogenic effects of the "ethion" residues and the expected protective role of the ethanolic extract of rosemary (Rosmarinus officinalis L.) (EER), in adult male rats. Feeding animals with Maize containing ethion residues (4 mg/Kg) caused elevation in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) activities (P<0.01, P<0.001 and P<0.01), respectively. Whereas total protein (T.P) and albumin (ALB) were significantly decreased (P<0.01 and P<0.05), respectively. As well as, an elevation in serum creatinine and urea levels (P<0.01). Also, a significant (P<0.01) increase in cholesterol, triglyceride and low density lipoprotein (LDL) and a significant (P<0.001) decrease in high density lipoprotein (HDL) content as compared to the control were obtained. In addition a decrease in plasma acetyl cholinesterase (P<0.01). Decrease in glutathione (GSH) ( P<0.01 ) , Superoxide dismutase (SOD), ( P<0.05 ), catalase (CAT) P ( P<0.01 ) and an increase in Malondialdehyde (MDA) ( P<0.01 ) were observed in liver , kidney and brain tissues, respectively as compared with controls. Supplementation with ethanolic extract of rosemary leaves (EER), effectively relieved most of the ethion-induced alterations. The histological investigation strongly confirmed the highly protective effect of the EER in the tissues of selected organs. These findings suggest that rosemary is effective in improving both the function and structure of the examined organs through their potent antioxidant effect.