The spermatogenesis is regulated by the hypotalamus-hypophysis gonadal axis, and the androgens play a fundamental role in their last stages. The administration of the antiandrogen flutamide interferes with the function of androgen dependent organs (Prostate (P) and Seminal Vesicle (VS)). In this study flutamide (10mg/Kg b.w.) was injected to 10 mice and vehicle to the controls (n=6). The mice were sacrificed at 24 (n=5) and 72 (n=5) hours. In testicular sections the tubular diameter (TD) and height of seminiferous epithelium (EH) were measured. P and VS were macerated, and concentrations of fructose (VS) and zinc (P) were determined. No significant difference exists in the DT among the groups. However, the 72 hrs group showed EH higher than the control (p < 0.01). The fructose is lower at 72 hrs (p < 0.01) interval, at which the biggest concentration of zinc is found (p < 0.01). The decrease of the EH could be explained by the detachment of the elongated espermatids, due to the blockade effect on the testosterone activity, without being reflected in the TD at this short interval. The decrease of fructose clearly shows the deprivacion of androgens, whereas the elevated concentration of prostatic Zn at 72 hrs suggests deficiency in the secretion of Zn to the seminal plasma