Stage IS testicular cancer is defined by the persistence of elevated serum tumor markers, including α-fetoprotein and/or β-human chorionic gonadotropin, after orchiectomy without radiological evidence of metastatic disease. Current treatment recommendations include cisplatin based chemotherapy up front but the recommendations are based on limited single center series. We retrospectively analyzed clinical and pathological characteristics, and long-term outcomes in 110 patients uniformly treated with primary chemotherapy between 1994 and 2016. The primary objective was to evaluate long-term disease-free survival. We also explored factors associated with the need for additional treatment. The elevated prechemotherapy tumor markers were α-fetoprotein in 48% of cases, β-human chorionic gonadotropin in 14%, and α-fetoprotein and β-human chorionic gonadotropin in 38%. Median α-fetoprotein and β-human chorionic gonadotropin values were 71 ng/ml and 80 mIU/ml, respectively. The IGCCCG (International Germ Cell Cancer Collaborative Group) prognostic classification was good in 94% of cases. Mixed nonseminomatous germ cell tumor was found in 78% of cases. Of the patients 103 achieved a complete response to chemotherapy. In 6 patients radiological signs of progressive disease developed during chemotherapy, while 8 experienced relapse after an initial complete response. At a median followup of 108 months 108 patients were alive and disease-free. Five and 10-year disease-free survival rates were 87% and 85 , respectively. The predominance of embryonal carcinoma in the primary tumor was the only factor associated with the probability of needing additional therapy. Stage IS testicular cancer is more commonly associated with elevated α-fetoprotein, an IGCCCG good prognosis and mixed nonseminomatous germ cell tumor. Treatment with cisplatin based chemotherapy leads to cure in most cases. However, a proportion of patients require the integration of additional therapies, including more frequently when embryonal carcinoma is not predominant.