The enzyme-linked immunosorbent assay (ELISA) is widely used in medical diagnostics. In order to reduce the diagnosis time and to lower the consumption of sample/reagents in an ELISA assay, a suction-type, automatic, pneumatically-driven microfluidic chip has been designed and fabricated in this study. The microfluidic chip integrates a multi-functional micro-transport/mixing unit, for transporting metering and mixing of samples and reagents in order to automatically perform the entire ELISA protocol. A new surface modification has been adopted which allows for a high processing capacity. The detection sensitivity for the dengue virus is found to be 10(1) PFU/ml, which is much better than a conventional ELISA assay (10(3) PFU/ml). The entire assay time is only 30 min, which is much faster than with 96-well microtiter plates (4 h). The consumed sample and reagent volume is only 12 μl, which is less than a conventional assay (100 μl). The development of this microfluidic chip may be promising for other immunosensing applications.