The prognostic impact of pretreatment hemoglobin (Hb) level and its changes during definitive radiotherapy was evaluated by univariate and multivariate analysis in the group of 453 FIGO IB-IIIB cervical cancer patients. Pretreatment anemia (Hb < 12 g/dl) was present in 148 patients (33%), and anemia at the end of irradiation in 48%; in 64% Hb level declined during therapy. Median overall survival in patients with initial Hb >or=12 g/dl was 66 months compared to 22 months in those with lower baseline Hb levels (p = 0.0001). This difference was mainly due to increased risk of distant spread in anemic patients (40% compared to 25% in subjects with pretreatment Hb >or=12 g/dl; p = 0.001). Baseline Hb >or=12 g/dl was also associated with longer disease-free survival and improved local control. Declining Hb level during radiotherapy predicted for impaired 5-year disease-free survival and local control probability. In multivariate analysis, low pretreatment Hb level remained associated with worse overall and disease-free survival, whereas adverse impact of declining Hb level on outcome was not observed. With regard to other clinical factors, stage and tumor extension (uni- or bilateral parametrium involvement for Stage III) were the only independent determinants of prognosis.