Postoperative hydrocele (PH) is the most common and important complication of surgical treatment of varicocele. It may form many years after procedure performed in adolescent boys. Among procedure modifications aiming at prevention of PH the authors describe formation of a 'window' in tunica vaginalis and lymphatic vessels sparing. the aim of the study was determination of true PH occurrence in long term results and evaluation of implemented modifications of surgical treatment aimed at decreasing the occurrence of this complication. material and methods. The analysis comprised 289 boys operated using the Palomo method between 1991-2007. Initially no modification aiming at PH prevention was used, between 2003-2005 a 'window' was created in tunica vaginalis and since 2005 the standard has become dyeing of the lymphatic vessels which enabled sparing of these vessels during surgery. We evaluated the frequency of PH formation basing on direct postoperative and long term results in our operated patients. Results. Out-patient records of 289 boys who had undergone primary varicelectomy between 1999-2007 were retrospectively reviewed. In the group of 237 patients operated using the standard method PH was diagnosed in 26 cases (10.98%). The results were not improved by introduction of a modification -creation of a 'window' in tunica vaginalis. Hydrocele formed in 4 out of 27 patients (14.82%). In 25 boys treated with modified method -lymphatic vessels dyeing and sparing -in early postoperative period there were no cases of PH. The analysis of 122 adult men treated in childhood, who had been followed for on average 8 years and 8 months after surgery, showed that the frequency of PH after standard Palomo procedure without any preventive modifications was 27.9% (34 out of 122 operated cases). conclusions. 1. Postoperative hydrocele is the most common complication of surgical treatment of varicocele, however comparison of results from different centres requires uniform diagnostic criteria. 2. Early evaluation of this complication after procedures without preventive modifications may not be reliable, as PH may form many years after operation (11% based on records from early postoperative period, 27.8% based on long term results). 3. Among the modifications aimed at prevention of PH formation lymphatic vessels sparing seems most effective (in 25 patients operated using this method no PH in early postoperative period was seen), however long term results must be taken into account.