A controlled, randomized, double-blind study was performed to assess the effect of the oral antifibrinolytic agent tranexamic acid in patients with amegakaryocytic thrombocytopenia as regards their need for platelet transfusions and the number of bleeding episodes experienced. Each patient served as his or her own control and received sequential, randomized courses of either tranexamic acid or an identical placebo. The need for platelet transfusions due to bleeding and the total number of bleeding episodes were compared for tranexamic acid and placebo courses. Patients received platelet transfusions at the discretion of their personal physician and kept detailed records of bleeding episodes. Of three patients who completed the full study, none had a reduction in the need for platelet transfusions. Moreover, in the eight patients who participated in the study, there was no reduction in number of bleeding episodes during tranexamic acid treatment as compared to the number with placebo. Our data indicate that the prophylactic administration of tranexamic acid does not decrease dependence on platelet transfusions or decrease bleeding episodes in patients with bleeding due to amegakaryocytic thrombocytopenia.