Objective: Renal toxicity and ototoxicity are considered as the main side effects of aminoglycoside antibiotics, such as gentamicin. The present study aimed to investigate the effect of co-treatment by origanum vulgare extract on the gentamicin-induced renal toxicity. Methods: Adult male Wistar rats in the weight range of 200 to 250 grams were randomly assigned into four groups (n = 8): control, renal toxicity (with the intraperitoneal injection of gentamicin [100 mg/kg/day], for eight days), co-treatment with OV extract and gentamicin vehicle (with the intraperitoneal injection of normal saline and OV extract gavage [40 mg/kg], for eight days), co-treatment with OV ethanolic extract (with the intraperitoneal injection of gentamicin [100 mg/kg/day] and OV extract gavage [40 mg/kg]), for eight days. The amount of urea, creatinine, sodium, potassium, and osmolality were measured in the plasma and urine samples. The left kidney was used for the histological study and the right kidney was used to measure MDA and FRAP. Results: treatment with OV ethanolic extract significantly decreased the blood concentrations of creatinine, urea, the absolute excretion of sodium, the fractional excretion of sodium and potassium, and MDA, compared with the renal toxicity group. Besides, co-treatment with ethanolic extract of origanum Vulgare significantly increased creatinine clearance, urinary osmolality, and FRAP, compared with the renal toxicity group. Conclusion: The oral co-treatment with ethanolic extract of origanum vulgare has a protective effect on gentamicin-induced renal toxicity. This effect can be induced by reducing the oxidative stress caused by free radicals and reducing the amount of lipid peroxidation caused by gentamicin.