The present study proved that desmopressin (DDAVP) (1 microgram DDAVP/12 h/5 días) does not affect ovary, testis and adrenal development in immature Wistar rats (17 days old), because the DDAVP does not modify the weight of the aforementioned organs as compared with the control group. Nevertheless, the male adults Wistar rats (80 days old) showed lower serum testosterone concentrations than the control group, after injection of 4 micrograms/day (2 micrograms/12 h) or 8 micrograms/day (4 micrograms/12 h) of DDAVP during a 5 days period time. Moreover, paradoxical significant lower concentrations of serum testosterone were found in 4 micrograms DDAVP/day-treated rats than in 8 micrograms DDAVP/day-treated ones. The former also showed a decreased number of spermatozoa as compared with the latter and with the control group. The percentage of mobile spermatozoa was lower in rats treated with both concentrations of DDAVP as compared with the control group. Therefore, desmopressin does not delay gonadal and adrenal growth in immature rats, but, at low doses, it affects the testicular function and the mobility of the spermatozoa in male adult rats.