A 62-year-old woman with an 8-year history of hypertrophic cardiomyopathy and recent septal myotomy and/or myectomy underwent simultaneous hemodynamic and two-dimensional and Doppler echocardiographic evaluation. Evidence of abnormal diastolic relaxation in the absence of obstruction or systolic cavity obliteration was observed. Two abnormal patterns of diastolic blood flow were detected: flow from the left ventricular outflow tract toward the left ventricular body during isovolumetric relaxation, and middiastolic blood flow from the left ventricular body toward the mitral apparatus. This case provides evidence of abnormal diastolic function and two patterns of abnormal diastolic blood flow in a patient with hypertrophic cardiomyopathy but without a systolic gradient or cavity obliteration. These findings support the importance of disturbed diastolic function in the pathogenesis of hypertrophic cardiomyopathy.