This study was designed to ascertain the contribution of hypertension to the early diastolic time intervals in asymmetrical apical hypertrophy (AAH). Eighteen patients with untreated AAH were categorized as those with (n = 13) and without (n = 5) hypertension. Isovolumic relaxation time and early diastolic filling were determined in four groups: normotensive subjects (n = 20), patients with essential hypertension (n = 20), AAH with hypertension, and AAH without hypertension. Early diastolic function was measured by the interval from the aortic closure sound (IIA, phonocardiography) to the opening of the mitral valve (MVO, echocardiography) and the interval from MVO to the O point of the apexcardiogram. The IIA-O interval was also calculated. Peak velocities in the rapid filling phase (R) and atrial contraction phase (A) were measured using two-dimensional Doppler echocardiography in the center of the mitral orifice in diastole. The MVO-O/IIA-MVO and A/R ratios were also calculated. 1. In the AAH with and without hypertension groups, the IIA-O, IIA-MVO, and MVO-O intervals were significantly prolonged. The IIA-O and MVO-O intervals in the AAH without hypertension group were more prolonged than were those in the AAH with hypertension group. In patients with essential hypertension, the IIA-O and the IIA-MVO intervals were prolonged, but there was no prolongation of the MVO-O interval. 2. The MVO-O/IIA-MVO ratio was lower in essential hypertension and in the AAH with hypertension groups, and significantly higher in the AAH without hypertension group. 3. There was no significant change of the R, A, and A/R in each group. These results indicated that prolonged left ventricular relaxation was distinguished in essential hypertension. In AAH with hypertension, the same prolongation was observed, but the disturbance of early diastolic filling was mild. It is suggested that apical hypertrophy has a possible association with hypertension, though it may more properly belong to cardiomyopathy.