The aim of this work was to study the intratesticular vascular flow and to estimate seminal plasma insulin like growth factor-1 (IGF-1) concentrations in men with obstructive and non-obstructive azoospermia. Correlation of testicular Doppler values and seminal plasma IGF-1 concentrations with test for testicular sperm extraction (test-TESE) was further evaluated. 50 males were included in this study; 40 infertile azoospermic patients including 30 with non-obstructive and 10 with obstructive azoospermia and 10 fertile men as a control group. Each azoospermic patient was subjected to ultrasound scanning of the testis with color Doppler analysis of transmediastinal artery (TMA), assay of IGF-1 in seminal plasma, testicular biopsy and test-TESE. The fertile controls were subjected as well to testicular ultrasound and color Doppler examination and assay of IGF-1 in seminal plasma.The peak systolic velocity (PSV) of TMAs was significantly lower in patients with non-obstructive azoospermia (2.2 cm/sec ± 2.7) than in those with obstructive azoospermia and in controls (7.9 ± 1.6 cm/sec and 8.1 ± 1.1 cm/sec respectively; P<0.01). Seminal plasma IGF-1 concentrations were significantly higher in patients with non-obstructive azoospermia (6.89 ± 2.31) than in patients with obstructive azoospermia (2.72 ± 2.1; P<0.05) and both concentrations were significantly lower than in controls (17.14 ± 6.98; P<0.0001). Unsuccessful sperm recovery in test TESE was observed in 12 patients who presented the worst pattern of gonadal failure. TMA PSV values < 1.6 cm/sec were observed in this subpopulation.In conclusion color Doppler analysis of the TMA and seminal plasma IGF-1 concentration are useful for distinguishing between obstructive and non obstructive azoospermia. Color Doppler analysis of TMA seems to be a prognostic tool that may predict the presence of spermatozoa within the testes of patients with non-obstructive azoospermia.