Objective: This study aimed to investigate the preventive effect of ethanol extract from dayak onion (Eleutherine palmifolia) on the number of Leydig cells and the diameter of seminiferous tubules in mice (Mus musculus) exposed to monosodium glutamate (MSG). Method: A total of 25 mice were divided into 5 groups. Group C- received only 0.5% CMC-Na. Group C+ was given 0.5% CMC-Na and 4 mg/gBW/day of MSG. Groups T1, T2, and T3 were administered dayak onion (Eleutherine palmifolia) ethanol extract at doses of 30, 60, and 120 mg/kgBW/day, respectively, along with 4 mg/gBW/day of MSG. All treatments were administered orally for 52 days. Result: The results indicated that MSG exposure resulted in a significant decrease in the number of Leydig cells and the diameter of seminiferous tubules in the C+ group compared to the C- group (p < 0.05). Administration of dayak onion (Eleutherine palmifolia) ethanol extract at doses of 30 (T1), 60 (T2), and 120 mg (T3) per kg BW showed similar results (p>0.05) to those of the C- group. Conclusion: In conclusion, the administration of dayak onion (Eleutherine palmifolia) ethanol extract mitigates the harmful effects of MSG on the number of Leydig cells and seminiferous tubules diameter in mice (Mus musculus) as a model. This research shows that Dayak onion (Eleutherine palmifolia) plays a role in reproductive health care.