The authors report their experience of 2D echocardiography in the acute stage of myocardial infarction. One hundred patients, 60 men and 40 women, aged 60 +/- 4.5 years (range 32 to 69 years) were admitted to hospital with an uncomplicated inferior myocardial infarction and underwent 2D echocardiography on admission and coronary angiography 15 days later. Ten patients were excluded because unsatisfactory quality of the echocardiographic images. Forty-seven patients had initial ST depression of at least 1 mm in leads V1 to V4 (Group I) and 43 patients did not show these electrical changes (Group II). There were no significant differences in the clinical findings or in the cardiovascular risk factors between the 2 groups. On the other hand, inaugural necrosis was commoner in Group II (p less than 0.03) and cardiomegaly and CPK elevation greater in Group I (p less than 0.02). 2D echocardiography demonstrated the same degree of posterior wall hypokinesia or akinesia in the 2 groups. Septal hypokinesia was observed twice as commonly in Group I (p less than 0.03) both at echocardiography and ventriculography. Haemodynamic and angiographic data showed that double and triple vessel disease was commoner (p less than 0.05), that left anterior descending disease was more severe (p less than 0.03), left ventricular end diastolic pressure was higher (p less than 0.02) and the ejection fraction lower (p less than 0.02) in Group I, compared with Group II.(ABSTRACT TRUNCATED AT 250 WORDS)