BACKGROUND Non-immunological and immunological diseases have been reported to present a level of serum C-reactive protein (CRP) higher than the base level. For both, this level can guide the diagnosis and prognosis. OBJECTIVE To test the value of serum CRP, by a high-sensitivity CRP assay, during a non-immunological disease, in order to understand if this level is significant during the non-immunological diseases. METHODS In this study, 50 patients were divided in two groups according to different specific illness: 25 patients with unstable angina (UA) and 25 with acute myocardial infarction (AMI) with and without metabolic syndrome associated. Plasmatic CRP measurement was made for every patient, following an immunoturbidimetric high affinity technique performed in a RX Daytona clinical chemistry analyzer by Randox. Statistical comparison of the serum CRP level between groups was done using a Student's t-test. An ANOVA test was used to value cardiovascular risk factors associated with the serum CRP level. A p < 0.05 was considered to be significant. RESULTS To each illness, patients were classified into five subgroups, based on their plasmatic CRP level: 0.014 to 3.9 mg/L, 4 to 7.9 mg/L, 8.0 to 11.9 mg/L, 12 to 14.9 mg/L, and higher than 15 mg/L. Patients with UA were 16 (64%), 2 (8%), 0 (0%), 5 (20%), and 2 (8%), respectively. And patients with AMI were 15 (60%), 3 (12%), 4 (16%), 3 (12%), and 0 (0%), respectively. Statistical tests performed did not have significant difference. CONCLUSIONS We have proved that the serum CRP level, determined by a high-sensitivity CRP assay, can be useful in early detection of inflammatory processes in immunological and non-immunological diseases.