The protein composition of human myocardium at some cardiovascular pathologies was studied by use of 2D electrophoresis. It was found that dilitation(al) cardiomyopathy and ischemia are both characterized by transferrin accumulation in myocardium and by enhanced expression of a protein with Mm 3 kD/pI 5. Besides that, at ischemic disease there was seen an elevation of the fetal isoform in the light chain of myosin. For one of the polymorphous protein systems, the occurrence rate changes were also recorded.