Testicular cancer comprises different neoplasms, depending on the cell of origin and the typical age at presentation, but germ cell-derived tumors constitute the vast majority of cases. Testicular germ cell tumors (TGCT) can be diagnosed in every age group, but more than 90% of cases occur in young men. These tumors, comprising seminoma and nonseminoma, are derived from germ cell neoplasia in situ (GCNIS). Pathogenesis of TGCT associated with GCNIS partly overlaps with that of other developmental disorders of the male reproductive system within the testicular dysgenesis syndrome (TDS). Testicular somatic cell neoplasms, known as sex cord-stromal tumors, are relatively rare, but can have endocrine manifestations, such as precocious puberty or gynecomastia. In addition to its malignant features, cancer of the testis represents a developmental, endocrine, and reproductive problem. These issues are the focus of this chapter, and emphasis is given to aspects that are of interest to endocrinologists, including pediatric endocrinologists and andrologists. Management of invasive testicular tumors is largely handled by urologists and oncologists, thus only general information on surgical treatment, radiotherapy, and chemotherapy is presented. Impact of cancer treatment on the endocrine system, co-morbidities, fertility issues, and quality of life issues are also briefly reviewed.