Objective. Varicocele, which is the abnormal dilatation of internal spermatic veins, is known as the most surgically correctable cause of male infertility. In the evaluation of testicular arterial and venous blood supply, the scrotal colour Doppler ultrasound (CDU) is a valuable diagnostic method. The aim of this study was to investigate how the testicular blood flow is affected after varicocelectomy, and the place of scrotal CDU in the follow-up after varicocelectomy. Material and methods. Thirty male patients who were diagnosed with left-sided varicocele were prospectively included in the study. Before the varicocelectomy, semen analyses were carried out, and peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI) were measured by CDU. In the third postoperative month, scrotal CDU and semen analysis were performed again and compared with the preoperative results. Results. The arterial flow parameters PSV and EDV increased significantly, and the resistance parameters RI and PI decreased significantly, compared with the preoperative values. Sperm concentration, progressive motility and normal morphology improved in the postoperative semen analysis compared with the preoperative results. The increases in all three parameters were statistically significant. No statistically significant difference in vascular parameters was seen between the patients with improved and unimproved semen analysis. Conclusions. As confirmed by the results of semen analysis and CDU, testicular blood flow increases after varicocelectomy, resulting in the recovery of the haemodynamics of the testicle. CDU, which is generally used for diagnosis in the varicocele, can also be a valuable method of determining treatment success after surgery.