We studied the performance of the CARDIAC STATusTM, a new rapid, easy to perform qualitative whole blood bedside test for detection of elevated CK-MB and myoglobin in the emergency room. Blood samples from 182 consecutive patients with chest pain were drawn on admission and at five and seven hours after the onset of symptoms. The CARDIAC STATusTM tests were performed by coronary care unit nurses and, independently, by a trained laboratory technician. The results were compared with quantitative assays for CK-MB mass and myoglobin. At the end of the study, a second test series using a new lot number of cartridges was performed on the same blood samples because of possible elution buffer contamination. Nurses produced more false negative results than the technician (CK-MB 43 vs. 27 %, p=0.01, myoglobin 31 vs. 13 %, p<0.0001), but the technician produced more false positive myoglobin results (9.3 vs. 5.5 %, p=0.0001). In the second test series, the nurses produced significantly fewer false negative tests both for CK-MB (19 %, p<0.0001) and myoglobin (13 %, p=0.0002). The false negative rate for the technician was not different between the first and the second test series. The CARDIAC STATusTM yields a substantial number of false negative results both for CK-MB and myoglobin when compared to a quantitative assay, and therefore at present has limited value for ruling out an acute myocardial infarction.