For patients with a clinical stage 1 non-seminomatous germ cell tumour of the testis cure rates should be close to 100%, whether surveillance, primary surgery, primary chemotherapy or a combination is chosen. The identification of patients with microscopic metastases is difficult. Even with the best predictive factors currently available (vascular invasion and percentage embryonal cell carcinoma in the primary tumour), the identification of micro-metastases is no better than the flip of a coin. Several additional prognostic factors have been studied, but none is yet applicable in daily practice.