In 2006, by the news of National Center of Health Development, morbidity of cardiovascular disease was 501.84 per 10000 people. It’s increased by 2 times than over 10 years.Goal: To study and to determine stereometric research, mathematic modeling and histologicalcharacteristic on cardiomyocyte of arterial hypertension (AH), acute myocardial infarction (AMI) and chronic rheumatoid fever (CRF).Materials and Methods: It was prepared sections for histometric materials from muscular of left ventricle. Linear measurement and number of cardiomyocyte per area of materials were carried out by computermicroscope “Leica” with program Diskus 3.2 version from German. On linear measurement of AH, AMI and CRF were processed by mathematic modeling. On ratio of cytoplasm and nucleus and histological characteristics were analyzed by chi-square testResults: Results of stereometric research on cardiomyocyte On AH volume of cardiomyocyte was 5788.22±40.99mkm3, volume of the nucleus - 806.47±12.86mkm3, ratio cytoplasm and nucleus 1:7 and number of cells per area was 10.On AMI volume of cardiomyocyte was 3240.94±48.96mkm3, volume of the nucleus - 693.85±12.76mkm3, ratio cytoplasm and nucleus 1:5 and number of cells per area was 16. On CRF volume of cardiomyocyte was 5341.06±63.4mkm3, volume of the nucleus - 801.5±15.96mkm3, ratio cytoplasm and nucleus 1:7 and number of cells per area was 11. In comparatively healthy condition at 20 to 30 years old population of Mongolia the volume of cardiomyocyte was determined 1063.17mkm3, volume of nucleus 406.69mkm3, ratio cytoplasm and nucleus 2.6 and number of cells per area was 31. Result of histological research of myocardial muscle. By the research of the difference between histological characteristic was confirmed that all of this characteristics have real main difference. Conclusions: It was confirmed difference with statistical probability by that determined volume of the cardiomyocyte 5788.22±40.99mkm3 in AH, 3240.94±48.96mkm3 in AMI and 5341.06±63.4mkm3 in CRF. Quantity of cells per area was in AH - 10, in AMI – 16 and in CRF 11, but in comparatively healthy condition it was 31.