Purpose: To evaluate whether components of Testicular Dysgenesis Syndrome (TDS) affect testicular germ cell tumor (TGCT) prognosis and oncological outcomes. According to the hypothesis called TDS; undescended testis, hypospadias, testicular cancer and spermatogenic disorders share the same risk factors and have a combined fetal origin. Materials and Methods:We retrospectively evaluated the stages and oncological outcomes of 69 patients who underwent radical orchiectomy between January 2010 and December 2014 due to TGCT in our department. The presence of undescended testis, hypospadias and semen parameters disorders were recorded according to anamnesis of patients. Results: Among 69 patients with TGCT, only 16 (23.1 %) had TDS. Significantly higher rate of TDS (36.1 % vs. 9.1 %) was observed at the advanced stages of TGCT(p=0.008). In the TDS group, the rates of local recurrence (50 % vs. 11.3%, p<0.001), distant metastasis (93.6% vs. 3.8%, p<0.001) and cancer-spesific mortality (87.5% vs. 3.8%, p<0.001) were found significantly higher than those without TDS. The predicted time for recurrence-free survival (13.70 +/- 5.13 vs. 100.96 +/- 2.83 months, p<0.001) metastasis-free survival (13.12 +/- 4.21 vs. 102.79 +/- 2.21 months, p <0.001) and cancer-specific survival (13.68 +/- 5.38 vs. 102.80 +/- 2.19 months, p<0.001) were also statistically lower in this group. Conclusions: According to our preliminary results, there is an apparent relationship between TDS and tumor prognosis. Even if the components of TDS alone did not contain poor prognostic features for TGCT, the presence of TDS was found as the most important independent predictive factor for oncological outcomes in both seminomas and nonseminomas as well as all patients with TGCT.