Authors presented the basic criteria for indicating thrombolytic therapy in patients with acute myocardial infarction according to literature data and their own experience regarding the judgment of changes in initial standard electrocardiogram (without any changes after administration of nitroglycerine and/or chest pain resolution). They are: 1. ST segment elevation > or = 0.1 mV, in at least two contiguous leads, 2. new or a presumably new bundle branch block, 3. ST segment depression in thoracic leads V1-V3 in the presumptive presence of acute posterior myocardial infarction. It is appropriate to repeat the recording, to perform echocardiography (or coronary angiography) and to evaluate in complexity the general clinical status in case of nonspecific changes on the electrocardiogram. Authors include a review of literature data on evaluation of cases with successful thrombolysis based on standard electrocardiogram. They emphasized strongly the meaning of a fast and sustained decrease/normalisation of ST segment and/or presence of so called reperfusion arrhythmias (namely early, frequent, repetitive accelerated idioventricular rhythm). The authors presented also the changes of QRS complex, T wave and Q-T interval with thrombolytic therapy. The evaluation of ST segment re-elevation during and after thrombolytic therapy still requires to be studied into greater detail. (Tab. 5, Ref. 65.)