A retrospective study was carried out on 386 patients with advanced cervical carcinomas treated with radiation therapy between 1973 and 1983. The influence of hemoglobin concentrations and blood transfusions before and/or during treatment on the occurrence of distant and/or local regional failures were examined in a univariate and multivariate analyses. In the multivariate analysis hemoglobin concentrations were prognostic only during treatment and patients with at least one value below the threshold of 10 gm% had a significantly higher risk of local regional failure than the patients with all their values above the threshold. Moreover 70% of these high risk patients had less than half of their values below the threshold. It is possible that blood transfusions might be beneficial when given before treatment. However, although it was not significant, blood transfusions given during treatment tended to be an adverse prognostic factor suggesting that blood transfusions might not have completely offset acute anemia prior to transfusion. Our study suggests that anemia during treatment, even of short duration might be detrimental to patients.