Aims: To evaluate the prognostic value of haemoglobin levels during radio-chemotherapy for overall survival, metastases-free survival (MFS) and locoregional control in patients with locally advanced oesophageal cancer. Materials and methods: Age, gender, performance status, tumour location, tumour length, histology, histologic grading, T-stage, N-stage, UICC-stage and weekly haemoglobin levels during concurrent radio-chemotherapy were retrospectively investigated and related to outcome in 108 patients, who received radio-chemotherapy for stage II/III oesophageal cancer. Radio-chemotherapy consisted of 59.4-60 Gy irradiation, two to four courses of cisplatin (75 mg/m(2) on day 1) and 5-fluorouracil (1000 mg/m(2) on days 1-5). Haemoglobin levels during radio-chemotherapy were compared among the following three groups: patients with over 60% of haemoglobin levels less than 12 g/dl; patients with over 60% of haemoglobin levels at 12-14 g/dl; and patients with over 60% of haemoglobin levels greater than 14 g/dl. Results: On univariate analysis, haemoglobin levels of 12-14 g/dl and greater than 14 g/dl during concurrent radiochemotherapy provided better outcomes than haemoglobin levels less than 12 g/dl. The 2-year overall survival rates were 34%, 35% and 16%, respectively (P = 0.002). The 2-year MFS survival rates were 23%, 46% and 21%, respectively (P = 0.06). The 2-year locoregional control rates were 44%, 58% and 19%, respectively (P < 0.001). ECOG performance status (1 better than 2-3) was significantly associated with overall survival (P = 0.013), tumour length (< 7 cm better than >= 7 cm) with overall survival (P = 0.002) and MFS (P = 0.002), N-stage (N0 better than N1) with overall survival (P = 0.004) and MFS (P < 0.001), and UICC-stage (stage II better than III) with overall survival (P = 0.025) and MFS (P = 0.010). On multivariate analysis, haemoglobin levels during radio-chemotherapy maintained significance for overall survival (P = 0.002) and locoregional control (P < 0.001), tumour length for overall survival (P = 0.002) and MFS (P = 0.008), and N-stage for MFS (P = 0.003). Conclusions: Haemoglobin during radiotherapy and concurrent radio-chemotherapy is an independent prognostic factor in oesophageal cancer treatment. To improve outcome, it seems important to maintain the haemoglobin at 12-14 g/dl.