Summary: Masculine infertility is a common and complex problem that affects 1 in 20 men. Despite research in this area, in most cases, the causes are unknown. The literature describes many natural products used in folk medicine to treat sexual dysfunctions. There are various studies with propolis, produced by the bee, Apis mellifera. Here, we investigate whether propolis consumption during gonad maturation could interfere with sperm production in the mature animal. Therefore, the animals began their treatment with 21 days of age, onthe first weening day, divided into two groups, control and treated rats, receiving 6mg/Kg/day of propolis. The treatment lasted 69 days, and they were euthanised when completing 90 days of age. For sperm count, testicles were removed, weighed, homogenized and diluted. The homogenate was placed in a Neubauer chamber and the spermatids of five fields were counted, per sample. Sperm quantity was calculated according to this count. The results showed significant numerical reduction of spermatozoa, according to all the analyses of the treated rats, compared to the controls. Diminished sperm count per testicle, per gram of testicle and lower daily sperm production were found. Studies of adults treated with propolis have suggested a rise in steroidogenesis, bettering sperm production and increasing testosterone levels in rats and rabbits. Other research projects affirm that propolis increases sperm production and interferes with the morphology of the initial portion of the epididymis head. All these studies were made using adult rats. In the present research, we evaluated the effect of propolis during gonad maturation and concluded that propolis administered during this period interferes with the production of spermatozoa in these rats as they attain maturity, due to the smaller quantities of spermatids in the testicles. Other analyses will be made to complete the research of alterations caused by própolis.