The present work explored the characterization, antioxidant and protective effects of edible Rumex roseus on erythrocyte oxidative damage induced by methomyl in mice. In a preliminary in vitro study, luteolin and ferulic acid were detected, using HPLC–DAD, as the most abundant phenols; Rumex roseus extract showed also a promising antioxidant effect. In the in vivo experiment, mice were subjected to methomyl intoxication demonstrating a significant decrease in red blood cells, hemoglobin and hematocrit levels coupled by a significant increase in bilirubin, LDH, osmotic fragility, reticulocyte and white blood cells number. Erythrocyte specific alterations were also detected as sphercytosis, schistocytosis, dacryocytosis and Howell-jolly bodies; these features are characteristic of a normocytic normochromic regenerative anemia. The oxidative status was also altered, showing a significant increase in malondialdehyde concentration, GSH level and SOD activity while CAT and GPx activities significantly decreased. All the above-cited alterations showed signs of reversal when mice received the methanolic extract of Rumex roseus. The present data suggest that Rumex roseus could be classified as a novel functional food due to its dual role; further to being traditionally used as a flavor food, it was proven by the present work that the new Rumex was capable to alleviate mice erythrocyte oxidative stress known as one of the most critical health issues.