Recently, a rapid bedside assay for quantitative determination of cTI and CPK-MB has been developed that provides a positive or negative result in 10 to 15 minutes allowing for a better therapeutic approach. The objective of our study was to validate the diagnostic usefulness of cardiac troponin I in patients with chest pain. We determined sensitivity, specificity, positive and negative predictive values in 40 patients that arrived to the hospital with chest pain. These patients were assigned to four different groups: Group A: Patients with acute myocardial infarction. Group B: Patients with unstable angina and normal ECG. Group C: Patients with atypical chest pain and normal ECG. Group D: Control. Eighteen (45%) patients were woman and 22 (55%) were men; age 54.1 +/- 26, range 32 to 85 years. In Group A, sensitivity, specificity, positive and negative predictive values for cTI were 95%, for CPK-MB, they were 40, 50, 90, 7.1%. For Group B, cTI: 64, 90, 90, 64%; CPK-MB: 50, 90, 87, 56%. Group C, cTI and CPK MB 25, 95, 50, 86%. Group D, cTI and CPK-MB: 50, 95, 50, 95%. This study suggests that the rapid bedside qualitative test through cardiac troponin I assessment is a test with higher predictive value for early diagnosis of acute myocardial infarction than CPK-MB.