Background: The purpose of this study is to determine the frequency of underlying hematological disorders as the cause of acute adolescent menorrhagia. Methods: The records of 25 patients that were hospitalized with acute adolescent menorrhagia in the Obstetrics and Gynecology Department of Cerrahpa¸sa Medical School of ˙Istanbul University between 1988 and 1995 were analyzed. Results: The mean age of the patients was 13.9±1.6 (SD) years. A hematological abnormality that caused bleeding diathesis and acute menorrhagia was diagnosed in 7 of the 25 patients (28%). There were four cases of immune thrombocytopenic purpura, two cases of Van Willebrand disease and one case of acute promyelocytic leukemia. All seven patients with a coagulation disorder required blood transfusions and the mean hemoglobin level at presentation was 6.2 g/dl.