The frequency and importance of prolonged bleeding time were studied in patients affected by a severe anemia (haemoglobin less than 8 g/dl). A Simplate bleeding time test was performed in 25 patients suffering from various haematological disorders, with a platelet count greater than 100,000/cu mm and a normal or increased factor VIII complex. Patients with acute leukaemia, myeloproliferative disorders or chronic renal impairment were excluded from the study. Bleeding time was prolonged in 12 patients; their mean haematocrit was not different from that of the 13 other patients whose bleeding time was in the normal range. Bleeding time was less prolonged than in patients with chronic renal insufficiency in spite of a lower mean haematocrit (previous study). Fifteen patients were investigated a second time after partial or full correction of the haematocrit; in all but one, the bleeding time was reduced and/or normalized. This study suggests that severe anaemia may be an additional hemorrhagic risk factor in patients with another cause of bleeding.