Purpose: To assess the value of hemoglobin concentration (HC) in predicting treatment outcomes in nasopharyngeal carcinoma (NPC) patients treated with chemotherapy (CT) and radiotherapy (RT). Patients and Methods: Ninety-eight NPC patients treated with three courses of platinum-based neoadjuvant CT (NCT) and conventional RT were grouped as having normal HC (greater than or equal to12.0 g/dl in females and greater than or equal to13 g/dl in males), having mild anemia (MA) (13.0 g/dl>Hbgreater than or equal to11 g/dl in males, 12.0 g/dl>Hbgreater than or equal to11 g/dl in females) and having severe anemia (SA) (Hb <11 g/dl). Massive decrease in HC (MDHC) was defined as greater than or equal to1.5 g/dl decline with NCT Along with other known risk factors (sex, age, histopathology, T stage, N stage, bilateral neck involvement, cranial nerve involvement and total RT time), the prognostic value of SA and MDHC were evaluated by Cox-regression. Results: SA increased from 7 to 33% with NCT (p<0.0001). Patients with SA had lower 5-year locoregional control (LRC) (49 vs. 73%, p=0.03), disease-free survival (DFS) (42 vs. 68%, p = 0. 01) and overall survival (OS) (43 vs. 69%, p = 0.01) rates than patients with normal HC or MA. The presence of MDHC worsened 5-year LRC (p=0.002), DFS (p=0.001) and OS (p=0.02) rates. In multivariate analyses, MDHC and SA had pronounced effect on LRC and survival, respectively. Conclusion: MDHC and SA adversely affect treatment outcome in NPC patients treated with CT and RT This may favour concomitant scheduling of RT and CT over neoadjuvant setting. Correction of HC before RT can improve the efficacy of RT and should be further evaluated.