At present patients in whom a testicular germ cell tumour in clinical stage I is diagnosed have a long-term survival rate of 98%. For non-seminomatous germ cell tumours in this stage three different treatment options are available: primary retroperitoneal lymphadenectomy (PRLA), the wait-and-see strategy, and primary adjuvant systemic chemotherapy. These therapeutic approaches do not obviously differ in the long-term survival rate of the patients. Abdominal CT scans yield false-negative results in 20-30% of patients with occult metastases. The identification of certain histological characteristics within the primary tumour (vascular and/or lymphatic invasion, presence of embryonal carcinoma, absence of yolk sac elements) allows stratification of patients into groups at high and low risk for tumour progression and/or the presence of retroperitoneal lymph node metastases. The determination of biological and genetic characteristics of the primary tumour in addition to classic histological parameters, does not actually seem to reveal any further prognostic information relating to the biological behaviour of the individual tumour. Therefore, with regard to the outcome of prospective and retrospective MRC studies, patients should be stratified according to the Freedman score into groups at high and at low risk of tumour progression and consequently undergo an aggressive (retroperitoneal lymphadenectomy/systemic chemotherapy) or less aggressive (wait-and-see) treatment adjusted to the aggressiveness of the individual tumour. Prospective studies should be performed to find whether biological characteristics of the primary tumour might reveal any additional prognostic information superior to that yielded by histological parameters and possibly allow an even more subtle classification of the patients into high- and low-risk groups.