The groups of patients with myocardial infarction (MI) and hypertrophy of the left ventricle (HLV) (n = 45 and n = 53, respectively) and a sample of healthy individuals from the Moscow population (n = 60) were examined for T174M polymorphism of ACT gene (replacement of methionine for threonine at position 174 of the correspondent amino acid sequence). In MI patients the content of 7T genotypes and 7 allele was significantly lower than in the control group (57.8% against 80% and 67.9 against 89.2%, respectively), whereas the proportion of M allele and TM hétérozygotes was increased (32.1 against 10.8% and 37.8 against 18.3%, respectively). In patients with HLV, the proportion of 7T genotype (64.2%) and T allele (77.4%) was also lower than in the control group, whereas the frequency of M allele was increased (22.6%). Our results suggest that the T174M polymorphism of ACT gene is associated with MI and HLV in the Moscow population.