Testicular cancer is one of the most common prevalent malignancies in young men, particularly among 15–35-years-old age group. Germ-cell tumors account for more than 95% of testicular cancers, which include both seminomas and non-seminomas. The incidence has increased over the past three decades, particularly in Western countries. This chapter describes the epidemiology, pathophysiology, clinical presentation, diagnostic methods, staging, and management of seminomas. The peak incidence of seminomas is between the ages of 35 and 39 years. The tumor markers like alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG), and lactate dehydrogenase (LDH) play a critical role in diagnosis, staging, and prognostication. Seminomas are typically treated with radical inguinal orchiectomy. There is a limited role of retroperitoneal lymph node dissection (RPLND). Stage I seminomas may be managed effectively with surveillance alone in the adjuvant setting, offering excellent survival rates. While more advanced stages (Stage II & III) require radiation therapy or chemotherapy as adjuvant treatment. Chemotherapy regimens such as BEP (bleomycin, etoposide, and cisplatin) have proven effective in advanced disease. This chapter also outlines the use of modern radiation techniques like 3D conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) for precise tumor targeting.