Alfa fetoprotein (AFP), human chorionic gonadotropin (HCG), beta HCG and lactate dehydrogenase (LDH) are powerful markers of germ cell tumors. The role of tumor markers is very important in the diagnosis, treatment and follow-up of germ cell tumors, respectively. We can often deduce the histological typing of germ cell tumors by tumor marker elevation before surgery. Tumor markers also frequently provide clues as to outcome in individual cases before treatment. The half-life of tumor markers during chemotherapy indicate the effect of the treatment. The optimal regimen of chemotherapy should therefore be selected based on the half-life of tumor markers. Normalized tumor markers designate the phase of discussion on surgical indications. Determination of tumor markers is important in following patients after treatment of germ cell tumors. The elevation of serum tumor markers denotes recurrence and is often the first sign of treatment failure.