A multivariate step-wise analysis with death or heart failure as prognostic end-points was utilized in 62 patients with an acute myocardial infarction (AMI), to evaluate the age related short-term prognostic significance of selected M-Mode and two dimensional echocardiographic parameters, and to identify, among them, the best predictors of the clinical outcome. The echocardiographic examination was performed within 24 hours from the occurrence of cardiac chest pain. After a three months follow-up study, the patients were divided into groups: 9 patients who died (Group A), 53 patients who survived (Group B), subdivided into 41 asymptomatic patients (Group B1) and 12 patients with clinical signs of heart failure (Group B2). The selected parameters were: age, left ventricular end-diastolic and end-systolic diameters (LVEDD, LVESD), left atrial diameter (LAD), the electrocardiographic PR interval minus AC interval from the mitral echogram (PR-AC), the distance between the mitral E point and the septum (EPSS), total aortic excursion (TAE), and two dimensional wall motion score. From the step-wise analysis of groups A and B we classified the parameters as follows, the relative prognostic significance being highest on the left side: score greater than TAE greater than AGE greater than PR-AC greater than LVEDD (LAD, LVESD, EPSS). For groups B1 and B2 the following results were obtained: score greater than PR-AC greater than AGE greater than LVESD greater than EPSS (TAE, LVESD, LAD). In parenthesis are indicated the variables whose prognostic value did not reach any significant level. When a discriminant function was applied to the 5 most significant variables, we could identify 78% of the patients of group A, and 77% of those of the group B; of groups B1 and B2 we identified correctly 83% and 92% of the patients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)