Seminal vesicle secretion is important for increasing the stability of sperm chromatin, inhibition of the immune activity in the female reproductive tract and so on. Metronidazole (MTZ), a drug used for treatment of infections caused by anaerobic bacteria and protozoa, may have negative effects on the genital gland including the seminal vesicles. Curcumin exhibits antioxidant as well as anti-inflammatory properties. The present study aims to evaluate the negative effects of MTZ on the seminal vesicle structure and ameliorative effects of curcumin using stereological methods. Thirty balb/c mice were divided into six groups. The control group was received distilled water. The second and the third received higher doses of MTZ (500 mg/kg body weight/day) and MTZ (500 mg/kg/day) + 100 mg/kg/day curcumin, respectively. The fourth and the fifth were treated with lower doses of MTZ (165 mg/kg body weight/day) and MTZ (165 mg/kg body weight/day) + curcumin (100 mg/kg body weight/day), respectively. The sixth group received 100 mg/kg body weight/day curcumin. All the administrations were done by oral gavages for 14 days. After 30 days, seminal vesicles were removed. Stereological study of the seminal vesicle structure revealed a significant reduction in gland and vesicular fluid volume in MTZ-treated (higher or lower doses) animals. Curcumin protected the reduction of both parameters in therapeutic-dose treated animals. Metronidazole treatment does not induce structural changes in the seminal gland; however, it can have a significant impact on its secretion ability. Importantly, these deteriorations might be preventable by curcumin co-treatment., Ali Noorafshan, Saied Karbalay‑Doust, and Literatura 30