This study was undertaken to determine whether abnormalities on the echocardiograms of patients with unstable angina have any prognostic significance. 27 male patients, mean age 53 years, who fulfilled criteria for unstable angina and who responded to medical therapy, had echocardiograms within 48 h of admission and at discharge. Follow-up data were obtained from 7 patients during a postdischarge period of 6-26 weeks. 13 patients had mild exertional angina or were pain-free (group I) and 14 patients had either severe, stable angina pectoris or recurrence of their unstable angina (group II) during the follow-up period. When admission and discharge values were compared, the echocardiographic ratio of left ventricular end-diastolic dimension to mitral valve closure time (EDD/PR-AC) showed significant differences for both group I and group II (p less than 0.05). An abnormal EED/PR-AC ratio was present at discharge in 8 of 14 group II patients compared to only 1 of 13 group I patients (p less than 0.05). The mean values for end-diastolic dimension, mitral valve closure time, and amplitudes of interventricular septal and posterior left ventricular wall motion were not significantly different in comparisons between admission and discharge studies and between group I and group II patients. In 19 patients who had cardiac catheterization druing the follow-up period, the discharge EED/PR-AC ratio correlated inversely with the angiographic ejection fraction (r = 0.79; p less than 0.001).