The composition of high-molecular complexes of aminoacyl-tRNA-synthetases (ARSase) from the rabbit liver was studied on the first day after reproduction of the experimental myocardium infarction. The studies revealed an increase in the glutamyl-, leucyl-, lysyl- and a decrease in the glycyl- and seryl-tRNA-synthetase activities and redistribution of the last two enzymes from the composition of the complexes into a lower-molecular fraction of postribosomal supernatant fluid. Under the experimental myocardium infarction the complexes reveal a significant decrease in the content of phospholipids and variations in the electrophoretic mobility of protein fractions. An assumption is advanced that a disturbed protein biosynthesis in the liver resulted from the experimental myocardium infarction causes changes in the structural organization of the ARSase complexes.