In this research, serum samples of one hundred patients with MI and one hundred patients with unstable angina were examined during the first 24-48 hours of hospitalization in the CCU of Panjum-e-Azar Hospital of Gorgan and CRP was measured using qualitative and semi quantitative methods. Using the qualitative test of CRP, in 85% of MI and 76% of unstable angina cases positive results had been attained and by using statistical surveys, it was concluded that the qualitative tests can be helpful in differentiation of MI from unstable angina. In addition, in the semi quantitative test, a meaningful relationship was found between CRP titres and MI diagnosis came about. Using the qualitative CRP test, a sensitivity of 85%, a specifity of 30%, a positive predictive value of 54.9% and a negative predictive value of 66% was attained. The CRP test in the form of qualitative and semiquantiative can be useful in the affirmation of clinical diagnosis of MI, but because of low specifity, complementary methods of diagnosis are suggested to be used along with this test.