Aplastic anemia is a disease characterized by general lack of bone marrow activity; it may affect not only the red blood cells but also the white blood cells and platelets, resulting in pancytopenia. Spontaneous gingival hemorrhage is present in some cases and it is related to the blood platelet deficiency. This case report presents the periodontal treatment of a patient with aplastic anemia. A 43-year-old female was referred for continuous gingival bleeding after periodontal treatment. Periodontal findings revealed generalized gingival imflammation, oozing of blood from gingival crevice, and it was diagnosed as adult periodontitis. Root planing and extraction of the upper left third molar with poor prognosis were put into operation after elevation of the platelet count with platelet transfusion. The extraction socket was sutured with 3-0 silk. Bleeding continued even after digital compression at the upper right second premolar, second molar, and left canine areas, which presented severe inflammation. Although platelets were transfused repeatedly, platelet count did not stay elevated since survival rate of the transfused platelets were low due to alloimmunization. Thrombin gauze packing was not effective. Bleeding ceased 3 days after treatment with transfusion of donor platelets. 20 days after the treatment, the gingiva was generally healthy except upper right second premolar and lateral incisor areas. The result of periodontal treatment was good, but bleeding control after treatment was troublesome. In the periodontal treatment of patient with aplastic anemia, elevation of the platelet count with platelet transfusion seems to be the best method for hemorrhage control.