Decrease in serum alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) levels is considered as a response during chemotherapy of non-seminomatous germ cell testicular tumors, bur data on the prognostic significance of marker half-life remains inconclusive. Serum marker half-life was evaluated in 34 patients with elevated markers, receiving chemotherapy (CT). Marker half-life was calculated from the natural logarithm of the sequential AFP or HCG concentrations. The correlation between event-free (EFS) and overall survival (OS) with unfavorable half-lives of AFP and HCG was evaluated. Median actual half-life (AHL) AFP was 3.9 days (range, 1.4-21.5) and median AHL HCG was 4.4 days (range, 1.4-21.0); 82% of the patients bad a satisfactory initial decline in AFP, and 71% had a satisfactory initial decline in HCG. There was a significant difference in EFS and OS between the two groups of patients with an AFP half-life <7 days and >7 days. HCG half-life did not adversely affect EFS and OS. The correlation of better EFS and OS with appropriate AFP marker half-life during chemotherapy could provide a dynamic method, which could complement the standard baseline prognostic factors; for the prediction of prognosis.