The aim of this study was to compare two protocols ofestrus synchronization in Santa Inês ewes. Thirty-eight ewes wererandomly divided into two groups of estrus synchronization: protocolPGF2α (two doses of 0.530 mg of PGF2α, nine days apart)and protocol MAP+eCG (intravaginal sponge impregnated withmedroxyprogesterone acetate, for 12 days, and then an injectionof 250 IU of eCG). The experiment was in a cross-over design,two estrous cycles apart. On the final day of protocol, a transrectalultrasound examination was carried out to measure the size of thelargest and second largest ovarian follicles and on day 7 of estrouscycle blood was collected to measure serum P4 concentration.Laparoscopy was carried out on day 11 after the end of protocols to count corpora lutea. Synchronization rate, size of largest andsecond largest ovarian follicles, interval between the end of theprotocol to estrus and ovulation rate did not differ between protocols.Ewes synchronized with MAP+eCG had greater serumP4 concentrations than ewes synchronized with PGF2α (3.9 and2.8 ng/mL, respectively, P<0.05). Based on the results, it may beconcluded that, although the protocol MAP+eCG was superior ininducing higher serum concentration of P4, the protocol PGF2αwas equivalent regarding estrus synchronization.