Thrombocytopenia in dengue infection raises concerns about bleeding risk. Of 256 patients with dengue infection who developed thrombocytopenia (platelet count, < 20 x 10(3) platelets/microL) without prior bleeding, 188 were given platelet transfusion. Subsequent bleeding, platelet increment, and platelet recovery were similar between patients given transfusion and patients not given transfusion. Prophylactic platelet transfusion was ineffective in preventing bleeding in adult patients with dengue infection.