160 survivors of acute myocardial infarction (AMI) were evaluated to assess the clinical significance of supraventricular tachyarrhythmias (SVTA) occurring at discharge from the hospital after the acute event. All the variables considered for the study were estimated before hospital discharge; arrhythmias were quantified with a 24 h Holter ECG monitoring system. SVTA occurred in 88 patients (55%). Single or repetitive supraventricular premature beats were found in 65 (41%), paroxysmal atrial or junctional tachycardias in 20 (12%), bouts of atrial flutter or fibrillation in 3 (2%). Bivariate statistical analysis showed no relationship between sex, previous cardiovascular history, type, and location of AMI and SVTA occurrence. A close positive relationship was found between age, left atrial dimension (LAD), cardio-thoracic ratio (CTR) and SVTA occurrence; an inverse relationship was found for left ventricular ejection fraction (LVEF). The presence of SVTA appeared significantly related to age above 55 years, to LAD greater than 40 mm, to LVEF less than 45%, to serum creatine kinase peak levels over 1400 U l-1 and to CTR over 0.49. Multivariate statistical analysis showed that five variables are important in discriminating patients suffering from SVTA: age, LAD, LVEF, left ventricular fractional shortening, and CTR. SVTA occurring at discharge from hospital after AMI are indicative of impaired left ventricular pump function.