This study was conducted to localize the testicular regions, which have better blood circulation by power Doppler ultrasonography in patients with nonobstructive azoospermia before testicular sperm extraction (TESE), and to investigate whether these vascularized areas have a high sperm retrieval rate or not. We evaluated 110 testes of 55 cases that were diagnosed as nonobstructive azoospermia. The mean age of the study group was 33 years (range 26 to 42). Patients with Y chromosome microdeletions, karyotype and hormonal abnormalities (except elevated FSH levels) were excluded from the study. In all cases, testes were evaluated by power Doppler ultrasonography before testicular sperm extraction. Testis was divided vertically into five equal parts and the area with maximum vascularity was determined subjectively. During testicular sperm extraction, starting from best-perfused areas, biopsies were done. If no motile or sufficient amount of sperm was found, TESE procedure was tried on the contralateral testis. TESE were performed from 82 testes and for the regions that show good and poor vascularity. The sperm finding rate was 38% and 14%, respectively (OR=3.55)(p=0.001). Power Doppler ultrasound mapping of the testis in nonobstructive azoospermic cases is a reliable and informative method to assess spermatogenic foci. It is a noninvasive technique that minimizes the unnecessary removal of hormone producing tissue and gives chance to end the TESE earlier than currently practiced procedures.