We present an electrochemical multianalyte or multiplexed immunosensor for simultaneous label free detection of cardiac markers panel, comprising of C-reactive protein, cardiac troponin-I and myoglobin. The multi electrode biosensor chip contains nine identical but electrically isolated microelectrodes arranged in a 3 x 3 array configuration. Each electrode contains carbon nanofiber nanoelectrodes grown vertically using plasma enhanced chemical vapor deposition. A hydrophobic photoresist layer, lithographically etched on the chip, exposes the electrodes and helps to selectively immobilize the antibody probes for the three target cardiac biomarkers using carbodiimide chemistry. The real-time label free detection of the three cardiac markers from a mixture is demonstrated with high sensitivity and selectivity. Detection in complex protein mixtures in human blood serum does not show any false positives from non-specific protein adsorption. The results show that the present sensor can serve as a miniaturized, low cost lab-on-a-chip system for the detection of various biomarkers in healthcare, environmental monitoring and security applications. Published by Elsevier B.V.