Objectives:To assess duplex ultrasound (DUS) parameters, and predicti the outcome of varicocele ligation in male infertility.Methods:This retrospective and follow up study was conducted at Dr. Sulaiman Al Habib Hospital, AlQassim, Saudi Arabia between January 2011 and December 2012. Eighty-two patients were selected, who presented with clinical/subclinical varicocele and male infertility. All these patients had DUS of the scrotum and underwent for low ligation varicocelectomy. These patients were followed for a period of 12-24 months after surgery for the occurrence of paternity. We reviewed pre-operative scrotal DUS of these 82 patients for the testicular size and volume, pampiniform veins caliber and duration of reflux in the dilated veins at rest, and after valsalva maneuver. These DUS parameters were correlated with the postoperative paternity rate.Results:Postoperative paternity was achieved in 18 patients (31.6%) with normal-sized testes, and in 3 patients (12%) with small size testes. The positive paternity rate was higher (38.5%) in patients with clinically detected varicocele, compared with only 16.7% of patients with subclinical varicocele (detected by ultrasound only). In addition, postoperative paternity was significantly higher in patients with bilateral varicocele (70.6%), with shunt-type varicocele (71.4%), and patients with a permanent grade of venous reflux (62.5%).Conclusion:Selection of patients for the successful paternity after varicocele repair depends mainly on DUS parameters, which includes normal size testicles with shunt type of bilateral varicocele and continuous reflux.