An increment of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) in human serum indicates an abnormal symptom of the liver. Hence, an electrochemical biosensor array that uses micro electro mechanical systems technology is required for rapid and integrated measurement of ALT/AST. Here we describe a biosensor array consisting of two glutamate sensors. It turned out that porous silicon layers formed on each working electrode were useful to increase the effective surface area. This biosensor array was constructed with platinum electrodes and a polydimethylsiloxane (PDMS) microchannel. Electrodes in sampling wells minimized a cross-interference effect and permitted multiple sampling by immobilization with glutamate oxidase using a silanization technique. The device sensitivities derived from semi-logarithmic plots were 0.145 microA/(U/l) for ALT and 0.463 microA/(U/l) for AST over a range of 1.3 U/l to 250 U/l. Hene, this ALT/AST biosensor array can be applied in diagnostic and home use.