The COG (Children's Oncology Group) currently recommends surveillance for all children and adolescents with clinical stage I testicular germ cell tumors. However, up to 30% of adults with clinical stage I testicular germ cell tumors harbor occult metastatic disease. In adults with clinical stage I nonseminoma some groups advocate a risk stratified approach. Occult metastases were noted in 50% of patients with features such as lymphovascular invasion or embryonal carcinoma predominance in the orchiectomy. However, to our knowledge there are no data on the impact of high risk features in such pubertal children and postpubertal adolescents. We reviewed an institutional testis cancer database for pubertal children and postpubertal adolescents younger than 21 years. We tested the hypothesis that lymphovascular invasion, or 40% or greater embryonal carcinoma in the orchiectomy specimen, would increase the risk of occult metastases, ie relapse during surveillance or positive nodes on retroperitoneal lymph node dissection. We identified 23 patients with a median age of 18.6 years (range 7.1 to 20.9) at diagnosis. Of these patients 14 (60.9%) were on surveillance, 9 (39.1%) underwent primary retroperitoneal lymph node dissection and none received initial chemotherapy. Seven patients (30.4%) had occult metastatic disease. High risk pathological features were found in the orchiectomy specimen in 12 patients (52.2%), including all 12 (52.2%) with 40% or greater embryonal carcinoma and 3 (13.0%) with lymphovascular invasion. Seven patients (58.3%) with high risk features had occult metastatic disease vs none (0%) without high risk features (log rank p = 0.031). Approximately half of pubertal children and postpubertal adolescents with high risk clinical stage I testicular germ cell tumors harbor occult metastatic disease. These results may be useful when discussing prognosis and treatment with patients and families.