Objective: To examine the correlation between the pulsatility and resistance indices (PI and RI) of the intraovarian artery on the day of follicle aspiration and the oocyte quality, intrafollicular oxidative stress, and luteinization. Pulsatility index and RI on the day of hCG administration also were measured. Design: Prospective study. Setting: Obstetrics and gynecology department of a university medical school in Japan. Patient(s): Thirty- five patients in an IVF- ET program. Intervention(s): The PI and RI of the intraovarian artery were measured by transvaginal color ultrasonographic pulsed wave Doppler on the day of hCG administration and the day of follicle aspiration. Follicular fluids and the granulosa cells were collected at follicle aspiration. Main Outcome Measure(s): The PI and RI of the intraovarian artery blood flowon the day of hCG administration and of follicle aspiration, as well as the rate of development of mature oocytes, follicular fluid steroid levels, and the incidence of apoptosis in the granulosa cells. Result(s): The PI and RI on the day of follicle aspiration were correlated positively with the rate of mature oocytes retrieved (PI: r = 0.429; RI: r = 0.348), were correlated negatively with the incidence of apoptotic mural (PI: r =- 0.383; RI: r =- 0.459) and cumulus (PI: r = - 0.378; RI: r =- 0.469) granulosa cells, and were negatively correlated with the concentration of P in the follicular fluid (PI: r =- 0.429; RI: r =- 0.359). The PI and RI on the day of hCG administration were negatively correlated only with the total number of retrieved oocytes (PI: r =- 0.393; RI: r =- 0.374). Conclusion(s): The PI and RI of the intraovarian artery blood flow measured on the day of follicle aspiration may be good indicators of the follicle luteinization and oxidation as well as of oocyte quality. Pulsatility index and RI on the day of hCG administration also Setting: Obstetrics and gynecology department of a university medical school in Japan. Patient (s): Thirty- five patients in an IVF- ET program. Intervention (s): The PI and RI of the intraovarian artery were measured by transvaginal color ultrasonographic pulsed wave Doppler on the day of hCG administration and the day of follicle aspiration. Follicular fluids and the granulosa cells were collected at follicle aspiration. Main Outcome Measure (s): The PI and RI of the intraovarian artery blood flowon the day of hCG administration and of follicle aspiration, as well as the rate of development of mature oocytes, follicular fluid steroid levels, and the inc idence of apoptosis in the granulosa cells. Results (s): The PI and RI on the day of follicle aspiration were positively correlated with the rate of mature oocytes retrieved (PI: r = 0.429; RI: r = 0.348) with the incidence of apoptotic mural (PI: r = - 0.383; RI: r = - 0.459) and cumulus (PI: r = RI: r = - 0.359). The PI and RI on the day of hCG administration were negatively correlated only with the total number of retrieved oocytes (PI: r = - 0.393; RI : r = - 0.374). Conclusion (s): The PI and RI of the intraovarian artery blood flow measured on the day of follicle aspiration may be good indicators of the follicle luteinization and oxidation as well as of oocyte quality.