Background: The aim of this study was to evaluate the efficacy of active surveillance after radical orchiectomy in patients with clinical stage I nonseminoma. Patients and Methods: Between 2002 and 2009, the charts of 80 patients who were offered active surveillance were studied retrospectively. Patients underwent clinical, radiologic, and biochemical examinations according to NCCN follow-up guidelines in nonseminoma. Results: 70 of 80 patients who accepted this strategy were analyzed. 12 of the 70 patients (17%) had relapses with a median follow-up of 18.5 months (6-76). Relapses were found in retroperitoneal lymph nodes in 3 patients. 5 patients had marker relapse, and 4 patients developed both marker relapse and retroperitoneal lymph node metastases. 10 of the 12 patients (83%) had relapsed within 1 year. There were no statistically significant differences in lymphovascular invasion and germ cell components between relapsed and non-relapsed patients. 11 of the 12 patients were treated with cisplatin-based combination chemotherapy, and 1 patient underwent retroperitoneal lymph node dissection. Only 2 patients underwent primary retroperitoneal lymph node dissection for rest nodules. Conclusions: Surveillance could be a reliable strategy in compliant stage I nonseminoma patients. Recurrences can be detected early and treated successfully.