Apical pulsed Doppler tissue imaging can be used to assess the function of regional myocardium. We hypothesized that septal dysfunction might be clarified in the hypertrophic cardiomyopathy (asymmetric septal hypertrophy) by this method. Twenty-one patients with asymmetric septal hypertrophy (mean age 54.8 +/- 11 years) and age-matched 24 normal subjects (52.4 +/- 8 years) were studied. The E/A ratio measured by mitral inflow Doppler was not different between the groups (1.1 vs 1.2). E wave velocities of the septum were significantly decreased in the hypertrophy group compared to the control group (4.0 +/- 1.5 vs 8.1 +/- 2.2 cm/sec), and A wave velocities were increased in the hypertrophic septum, resulting in a significantly lower E/A ratio (0.5 +/- 0.3) compared to the E/A ratio (0.9 +/- 0.3) of the normal septum. Deceleration time of the E wave and isovolumic relaxation time were significantly prolonged in the thick septum compared to the normal septum (136 +/- 51 vs 107 +/- 28 msec, 91 +/- 36 vs 63 +/- 19 msec, respectively). In conclusion, asymmetric septal hypertrophy was characterized by diastolic dysfunction of the thickened septum. Intramyocardial pulsed Doppler echocardiography can detect regional myocardial dysfunction earlier than the mitral inflow Doppler method.