Back grounds and objectives : Arthrosclerosis is the major cause of cerberovascular disorders and major problems of industrial countries. Mortality from chronic diseases such as arthrosclerosis and mortality from infectious diseases have a reverse, relationship with economic and educational levels of people. For this reason, investigating the relationship of MI with other risk factors such as infections has been of great interest.

  Methods: This was a case- control study. 60 patients with MI and 60 matched cases were selected from other wards of Boali Hospital. All of the patients who had been admitted with myocardial infarction diagnosis in the time of study were selected and information about them was recorded in a researcher made questionnaire. Serum sample from patients and control case were sent to determinations of IgG Anti Chlamydia antibodies with enzyme immune assay. Control case were selected from other wards of hospital who matched in age, sex and same test in serum sample was done.

  Results: In this study in each group 48 persons (80%) were male and 12 persons (20%) were female. The range of age group was 35-80. Mean age group was 58.83±12.6 (SD) and mean age of control tools was 59.08±11.59.All of the patients in each group had anti Chlamydia antibodies (IgG) (titer more than 5U/ml). The mean range IgG in both groups were compared through t-test and there was no significant difference between them (p=0.85).

  Conclusion: In this study all of the cases and controls had anti Chlamydia antibodies. (IgG) high prevalence due to cold climate and high crowd of people in this area may be related to Chlamydia infection.