Anemia is often associated with neoplastic disorders. Blood transfusions are used to alleviate the discomfort of anemic cancer patients. Of 246 terminally ill cancer patients admitted to our palliative care unit from October 1991 to December 1993 (128 women and 118 men), 31 patients (12.6%) (17 men and 14 women; age, 69.5 +/- 12 years) received on average 2.8 units of packed red blood cells (PRBCs) (range, 2-7 units/patient) in 35 separate admissions. PRBCs were transfused in the presence of low hemoglobin (Hb) levels ( < or = 8 g/dL) and/or severe fatigue or dyspnea. Pre-transfusion performance status, cognitive function, dyspnea, and fatigue at rest (evaluated by a four-point scale), complete blood count, serum albumin, and C-reactive protein were determined. The day after transfusion, subjective well-being was recorded as "yes/no" improvement in comparison with the pre-transfusion day. Improved subjective well-being after blood transfusion was reported in 51.4%, without significant relationship to pre-transfusion Hb levels or performance status. The influence of blood transfusion on subjective well-being was not related to the severity of dyspnea or fatigue. Twenty-one patients (60%), including seven with subjective improvement, died during the same hospitalization, a median of 49 days after transfusion. Pre-transfusion Hb level did not differ significantly in patients who benefited and did not benefit from transfusion, whereas time before death was significantly (P < 0.001) shorter in patients who did not benefit. In the discharged patients (40%), the median interval between transfusion and discharge was 13 days and the frequency of subjective improvement in well-being was 78.6%. Our data suggest that two main areas should be investigated, namely the relation between low Hb levels and symptoms and signs in terminally ill cancer patients, and the correct timing for effective blood transfusion. A combination of criteria is needed for effective transfusion; they must include not only Hb levels but also type and severity of anemic symptoms and signs. Furthermore, the identification of reliable prognostic indicators for survival would be useful.