Background: The management of testicular seminoma (TS) is evolving with guidelines supporting differential use of chemotherapy (CT) and radiotherapy (RT) depending on stage and presentation. We examined modern practice patterns in TS using the National Cancer Data Base. Methods: Data on 41,745 patients with TS treated between 1998 and 2010 were analyzed. Patients were grouped by stage based on National Comprehensive Cancer Network treatment guidelines. Multivariate generalized estimating equation models were used to assess factors associated with treatment paradigms. Results: Rates of surveillance after orchiectomy for those with stage IA/B TS increased from 21.4% during 1998-2001 to 40.4% from 2006-2010. Despite this, RT remained the most common adjuvant therapy (47.9% in 2006-2010). Use of adjuvant CT increased from 1.7% to 10.6% during this time. Patients with stage IS TS most commonly received RT; however, in 2006-2010, 32.4% of patients received surveillance and 15.6% received CT. Receipt of surveillance for those with stage IIA/B TS remained flat at ~12% while the use of CT rose (34.4% in 2006-2010 vs. 22.5% in 1998-2001). For patients with stage IA/B TS, Medicare or uninsured patients were more likely to receive surveillance vs. CT/RT (OR 1.54, p<0.0001 and OR 1.26, p<0.0001 respectively). Adjuvant CT/RT was more common at high volume centers (OR 0.63 vs. low volume, p<0.0001) and in patients with larger tumors (OR 0.80 for tumors ≥ 4 cm, p<0.0001). Among patients with stage IA/B TS who received adjuvant RT/CT, Medicaid or uninsured patients (OR 0.55, p<0.0001 and OR 0.68, p<0.0001 respectively) and those treated at NCI network cancer centers (OR 0.40 vs. community centers, p<0.0001) were less likely to receive RT vs. CT. For stage IIA/B TS patients, facility type was the strongest predictor for the receipt of RT vs. CT (OR 0.54 at NCI network centers, p<0.0001). Conclusions: Management of TS appears at least partially driven by economic concerns and facility type, especially in regards to selection of stage I patients for surveillance, the preferred management for this group. Many patients with stage IS are not managed according to published guidelines. Action is needed to ensure all patients with TS receive guideline supported care.