The ovarian activity of Agouti paca was characterized by hormonal profiles and ovarian structures. Samples of blood were taken from eight females (seven adults and one juvenile) at the breeding grounds of the Facultad de Medicina Veterinaria y Zootecnia in Yucatán, México. Sampling lasted approximately two months and was done every three and six days. Blood was collected from anesthetized animals, and the levels of progesterone (P4) and 17 β estradiol (E2) were analized by radioimmunoassay technique. Macroscopic and microscopic analyses were carried out in ovaries of dead animals. The estrous cycle lasted 29±8.4 days, levels of 1.61±0.65 ng/ml for P4 and 39±24 pg/ml for E2 were observed for a follicular phase, 6.18±3.70 ng/ml and 29±16 pg/ml for P4 and E2 respectively in the luteal phase. Statistically significant differences were found between phases for P4 but not for E2. The presence of extragonadal steroids with levels of P4 of 1.9±0.77 ng/ml and E2 of 22±17 pg/ml were observed, which are

not produced by the effects of managing stress. The changes in the levels of P4 during the cycle are indicators

of luteal activity, with the intersticial tissue acting probably as active steroids-producing gland.Follicular growth

was observed during the entire cycle.