AMP-deaminase (AMPDA) catalyzes the deamination of AMP to IMP and ammonia. Being an integral enzyme of the purine nucleotide cycle (PNC), AMPDA participates in catalytic deamination of amino acids and provides their involvement in a carbohydrate metabolism, fumarate being one of the end products of PNC. Since AMPDA competes with 5'-nucleotidase for AMP, it is responsible for regulation of a physiologically important active product of purine nucleotide metabolism, such as adenosine. Thus, this enzyme plays an important role in determining the physiological state of the organism in normal conditions as well as under the influence of some environmental factors and in some pathologies. The review sums up the information concerning the AMPDA participation in PNC operation in animal tissues, coding genes and enzyme activity regulation by various effectors, including, reversible phosphorylation and binding to myofibrils and myosin. Special attention is being given to a possible relationship of AMPDA activity deficiency to some neuromuscular pathologies.