Ultrasonographic real-time imaging and measurements of spermatic veins in the inguinal canal were evaluated in two groups of patients: 20 young men with varicocele and 18 controls. Examinations were performed with the patient in an upright relaxed position, and performing the Valsalva maneuver. The increase in diameter of the main vein during Valsalva maneuver was considered to quantitatively represent venous reflux. The data obtained were correlated with pre- and postoperative clinical findings. This method of evaluation proved to be a useful noninvasive diagnostic modality for detecting varicocele and for assessing treatment results. On the basis of venous diameters and reflux values, a classification of varicocele is proposed. Such an objective method of grading would eliminate the subjective impression and interpretation factors of the examiner.