To the Editor.— The presence of a hypercoagulable state in patients with a shortened activated partial thromboplastin time (APTT) as manifested by the clinical association with an increased incidence of thromboembolic disease has previously been reported by Hume, 1 Gallus et al, 2 Pilgeram, 3 McKenna et al, 4 and McKenna et al. 5 A recent review of patients' clinical records at Southern Nevada Memorial Hospital showed that rather than a history of thrombosis, patients with extremely short (less than 20 s) APTTs actually had a history of spontaneous bleeding. All APTT results that were of a coagulation panel were reviewed during a seven-month period from Jan 1 to July 31, 1979. All APTTs of less than 20 s were selected for evaluation of the clinical chart provided that the patient had a simultaneous normal prothrombin time (less than 13 s), to determine the cause for the hospitalization and the