Three trials were conducted to investigate the superovulatory response of Control Inter-nal Drug Releasing device (CIDRR). Forty-six Holstein cows were divided into three treatment groups per trial; CIDRR without progesterone (P4) (Control), CIDRR containing 1.9 g P4 for 12 days (CIDRR-1) and the two CIDRR with P4 replacing with a new CIDRR on day 9 of the 12 day insertion period (CIDRR-2). Follicle stimulating hormone (FSH) were administered on day 9 up to the time of CIDRR removal and additional prostaglandin F2α injections were done on day 11 of the 12 day insertion period. Ovulation rate, recovered and transferable embryos, and P4 and estradiol-17β (E2) levels in blood plasma were evaluated and compared among the treatment groups.There were no statistical differences on the mean (± SEM) ovulation rate, recovered and transfer-able embryos. An encouraging results of transferable embryos were obtained in the 3 treatment groups (80.7%, 69.8%, and 61.4% for Control, CIDRR-1 and CIDRR-2 respectively). No existing evidence of correlation between plasma P4 and ovulation rate at the time of AI (day 13) was observed. Plasma P4 and E2 concentrations were characterized by the physiological variability of individual cow and heterogeneous follicular development following superovulatory treatments. The results suggest that the use of CIDRR presents a satisfactory superovulatory regimen which could prove applicable for embryo production under field conditions. However, further research is necessary to elucidate factors involved in the improvements of the regimen.