This study aimed to determine the activity of the ethanol extract of Fenugreek Seed (Trigonella foenum-graecum Linn.) to reduce the sperm quality of young adult mice (Mus musculus) as a natural male contraceptive. This research is an experimental study using a post-test only control group design. The sample of this study consisted of 36 male Swiss Webster (Mus musculus) mice aged 2-3 months with a body weight of 20-30 grams which were divided into two groups randomly. The control group (P0) was given 0.5 ml of CMC Na 0.3% and the treatment group (P1) was given the ethanol extract of Fenugreek Seed (Trigonella foenum-graecum Linn.) 0.4 mg/gram BW as much as 0.5 ml for 36 day orally. The results showed that the administration of ethanol extract of Fenugreek Seed (Trigonella foenum-graecum Linn.) could reduce the quality (concentration, motility, viability, and morphology) of spermatozoa (P?0.05), so that Fenugreek Seed (Trigonella foenum-graecum Linn.) has potential as a natural male contraceptive.