INTRODUCTION: Adjuvant treatment for patients with stage I non-seminomatous germ cell tumors (NSGCT) could be active surveillance (AS), chemotherapy, or retro-peritoneal lymph node dissection (RLND). AS is the preferred option in most cas-es. The aim of this study was to evaluate long-term survival and prognostic factors in our population with AS approach. METHODS: We collected information from patients with stage I NSGCT of the testis in medical records from 1995 to 2016. Patients had negative serum tumor mark-ers and imaging of chest, abdomen, and pelvis with no evidence of metastasis. At relapse, if occurs, patients were treated with chemotherapy, surgery, or both. Kaplan-Meier method was used to estimate survival. Relationships with outcomes were analyzed using multivariable Cox regression and log-rank analysis. RESULTS: 457 patients were included. The median age at diagnosis was 25 years. The median follow-up was 65.3 meses (range 12 to 270 months). Relapses were detected in 92 (20%) patients with a median time to recurrence of 7.1 months (range 1.1 to 123 months). Retroperitoneal lymph nodes were the most common site of relapsed (41.3%), and most patients presented biochemical and imaging recurrence (67.4%). Vascular invasion (VI) was significantly associated with re-currence [HR 2.38 (CI 95%, 1.24-4.56), p=0.008] in the multivariate analysis, and rete testis invasion in the univariate analysis (p=0.027). After salvage treatment, 83 patients (91.1%) were disease-free. The overall survival was 98.25% at 20 years. CONCLUSIONS: AS is an effective non-adapted risk-based approach in patients with stage I NSGCT. Almost 100% are alive at 20 years. Nearly all relapses were cured with salvage therapy. Toxicity related to adjuvant treatments, as well as overtreatment, could be avoided.