This report presents a strategy for platelet support, which was used in patients suffering from acute leukaemia undergoing remission induction, and in patients treated by bone marrow transplantation (BMT) or by antithymocyte globulin (ATG). Platelet concentrates were produced from single donors by means of platelet pheresis with cell separators, with a yield of 3.0 to 4.0 X 10(11) platelets per platelet pheresis. Platelet support was investigated in 84 patients with acute leukaemia, median age 43 years (range 14 to 86), in 36 patients with BMT, median age 22 years (range 3 to 14) and in 6 patients treated with ATG, median age 40 years (range 11 to 44). Platelet transfusions were performed when the platelet count was about 20 X 10(9)/l, whether or not haemorrhage was present. When diagnostic puncture was performed or surgical intervention was necessary, platelets were given at a platelet count of below 80 X 10(9)/l. During remission induction the patients with acute leukaemia required, on average, 8 platelet concentrates, whereas in patients undergoing BMT the transfusion of 4 to 15 platelet concentrates was necessary, depending on the underlying disease. The requirement for patients treated with ATG was about 20 platelet concentrates. This strategy contributed to the low mortality of 3% from haemorrhage, despite the aggressive treatment.