To determine in acute myocardial infarction with an ST elevation (STEMI) treated with fibrinolytics frequency of ventricular premature beats (VPBs) and ventricular tachycardia (VT) according to the damaged area and residual cardiac function. With anterolateral infarction with ejection fraction (EF) < 45%, incidence of VPBs < 10/h was statistically significantly reduced (p < 0.001) while incidence of VPBs > or = 10/h as well as VPBs in a pair and VT was increased (p < 0.001). With anteroseptal infarction with EF < 45%, incidence of VPBs < 10/h was statistically reduced (p = 0.06) and incidence of VPBs > 10/h, VPBs in a pair and VT was increased (p = 0.06). With inferior and inferoposterior infarction with EF < 45%, incidence of VPBs < 10/h was reduced and incidence of VPBs > or = 10/h, VPBs in a pair and VT was increased. However, such difference was not statistically significant. Along with reduced residual cardiac function, one can also expect increase in frequency of VPBs and VT in all forms of STEMI regardless the area of damage. Such frequency is significant with all forms of anterior infarction, that is to say, slightly more with anterolateral infarction in relation to anteroseptal one. However, with inferior and inferoposterior infarction this frequency of VPBs i VT is not significant.