Although testicular cancer is a relatively rare tumor, it is the most common cancer among men aged 15 to 35 years. In the United States in 1989 approximately 5,500 men will be diagnosed with testicular cancer. Up until 2 decades ago, testicular cancer was the most common cause of a cancer death in this age group. The advances in diagnosis and treatment that will be described in this monograph represent one of the major achievements in the treatment of solid tumors. Testicular cancer is now one of the most curable of all cancers; the 5-year relative survival rate is in excess of 90%. In the U.S. fewer than 500 men will die from this disease in 1989. The primary goals in the treatment of testicular cancer as the 1990s approach will be to further decrease the mortality from this disease and to decrease the morbidity of treatment that has led to this dramatic improvement in survival.