The aim of this study is to evaluate the role of color Duplex and nitric oxide levels in seminal plasma and peripheral blood as a predictor for successful TESE. The study included, 40 azoospermic patients (20 cases with non-obstructive azoospermia and 20 cases with obstructive azoospermia), 40 oligozoospermic patient and 20 recently fertile men as a control. Nitric oxide levels and color duplex were useful to differentiate between obstructive and non-obstructive azoospermia.