Purpose: In spite of a high response rate to induction chemotherapy most seminoma patients with bulky abdominal disease have post-treatment masses. There are three available approaches in such a situation: close surveillance, additional irradiation of the residual mass, or surgery. We analysed our surveillance policy as a management method for post-chemotherapy residual masses. Patients and Methods: Fifty-seven patients with advanced seminoma were included in this retrospective analysis. All of them received induction chemotherapy with CI (carboplatin 400-600 mg/m(2) iv day 1 and ifosfamide 3 g/m(2) iv days 2 and 3 plus GM-CSF 5 mu g/kg sc days 4-15, cycles repeated every 3 weeks for 4 cycles) or EP (cisplatin 120 mg/m(2) iv day 1 and etoposide 100 mg/m(2) iv days 1-5 every 3 weeks for 4 cycles). Patients achieving a CR or PR were then managed by close observation. Results: Administration of CI or EP resulted in a complete remission rate of 33%. One patient developed disease progression and died, and 37 (65%) had residual abnormalities in the retroperitoneal area. With a median follow-up of 34 months (range 11-68) the 3 year overall survival is 94%. In 18 patients whose residual mass was less than 3 cm on postchemotherapy CT scan, the observation policy led to the complete disappearance of the tumour in 13 cases and 5 are alive with a persistent mass. In 19 patients with a residual mass more than 3 cm, complete disappearance of the residual abnormalities was observed in 3, 12 are alive with persistent disease and 4 patients presented with disease progression. Of these 4 patients two have died, one was salvaged successfully and one patient is still on salvage treatment. Conclusion: Based on the treatment results obtained in this group of patients with advanced seminoma we recommend the close monitoring of the residual mass and the administration of salvage chemotherapy and/or radiotherapy in cases of disease progression.