The rabbit liver tRNA was studied in such functional states when there occurred essential qualitative and quantitative changes in the protein synthesis. On the basis of the maximum level of aminoacylation it is established that the contents of corresponding biologically active individual tRNA in the total preparation for adult animals is 1.5-3 times as high as that for 3-5 day rabbits. Exception is alanine tRNA whose number decreases sharply in the total preparation of the liver tRNA of one- and two-year animals. No correlation was found for any age group between the quantitative ratio of active individual tRNA and the amino acid composition of albumins whose synthesis in the liver is intensive. Thus, the synthesis and, respectively, the content of certain types of tRNA in the liver characterized by a wide spectrum of proteins with different functions are governed by other regularities, whose search is one of the most difficult and at the same time high-promising problems.