Echocardiographic waves from the posterior left ventricular endocardium were recorded in 30 normal subjects and in nine patients during 13 anginal episodes. At rest the normal maximal systolic endocardial velocity (SEVM) was 6.2 ± 1.4 cm/sec, the mean systolic endocardial velocity (SEV) was 4.1 ± 0.7 cm/sec, and the systolic endocardial excursion (SEE) was 1.4 ± 0.3 cm. The maximal diastolic endocardial velocity (DEVM) was 18 ± 3 cm/sec, and the mean early diastolic endocardial velocity (DEV) was 9.4 ± 1.7 cm/sec. Exercise in 20 normals caused a significant increase in SEVM, SEV, DEVM, and DEV, but not SEE. In no instance did any of these values fall below the resting levels. The angina patients differed significantly from the normals having at rest a slower DEVM (15 ± 4 cm/sec) (P< 0.025) and DEV (8.4 ± 0.8 cm/sec) (P< 0.025). During exercise, but before angina, there was a significant increase in SEVM and SEV but not SEE, DEVM, or DEV. In no instance did any of these values fall below the resting levels. During angina SEVM and SEV reacted variably and together with SEE were not significantly different from the resting values. In contrast, there was a remarkable slowing of DEVM (8.2 ± 3.2 cm/sec) (P< 0.001) and DEV (5.7 ± 2.2 cm/sec) (P< 0.001). Five minutes after the pain and S-T-segment depression disappeared, the endocardium moved as it did before exercise.