Purpose: The prognostic significance of the rate of decline of the serum tumor marker alpha-fetoprotein (AFP) and human chorionic gonadotrophin (HCG) during the first two cycles of chemotherapy in germ cell tumor (GCT) patients was initially reported by us, but its value has been debated. We re-examined this issue in the context of the International Germ Cell Cancer Collaborative Group (IGCCCG) risk classification system and investigated the role of including in the analysis patients whose markers normalized early. Patients and Methods: One hundred eighty-nine GCT patients with elevated AFP/HCG marker values treated with platinum-based chemotherapy between 1986 and 1998 were included in this analysis. Patients were classified as good, intermediate, or poor risk by the IGCCCG criteria and as having satisfactory or unsatisfactory marker decline. Risk and marker decline were correlated with response, event-free survival, and overall survival. Results: Satisfactory marker decline predicted improved complete response (CR) proportion and eventfree and overall survival (P < .0001). The CR proportion, 2-year event-free, and 2-year overall survival rates for patients with a satisfactory and unsatisfactory marker decline were 92% versus 62%, 91% versus 69%, and 95% versus 72%, respectively. Marker decline remained a significant variable for all three end points when adjusted for risk (P < .01) with the outcome differences most pronounced in the poor-risk group. Conclusion: The rate of marker decline during chemotherapy has prognostic value independent of risk and may play a significant role in the management of poor-risk patients. It is appropriate to include patients whose markers normalized early.