The aim of this study was to investigate the effects of 10 mg/kg/week of nandrolone decanoate (DECA - Deca Durabolin®) on body composition, hormonal levels, spermatic parameters, redox status, and morphometric parameters of testicle and epididymis; furthermore, the fertility capacity of Wistar rats was measured thought in vitro fertilization (IVF). The animals (n = 16) were divided into two groups: control group (CTRL, n = 8), which received only vehicle composed by peanut oil and 10% of the benzoic alcohol and nandrolone decanoate group (DECA, n = 8), which received intramuscular injections of DECA for 8 weeks, both groups were treated for 8 weeks. The results demonstrate significative decrease in visceral fat, testosterone levels, and thiol content on epididymis, reduction on normal sperm parameters, and deleterious effect on testicles and epididymis tissue morphology showing reduction of germ height and luminal diameter on the DECA group. Thus, it can be concluded that high doses of nandrolone decanoate impairs male reproductive parameters.