For diagnostic and therapeutic purposes an accurate determination of multiple metabolites is often required. Amperometric devices are attractive tools to quantify biological compounds due to the direct conversion of a biochemical event to a current. This review addresses recent developments in the use of multiwalled carbon nanotubes to enhance detection ca- pability of amperometric array-based biosensors. More specifically, the principal techniques for multiwalled carbon nanotube incorporation onto microelectrode arrays are described. In these types of devices, each electrode is responsible for sensing one metabolite. The specificity is often given by an enzyme since most bio- molecules are not electroactive compounds. Common strategies for the protein immobilization onto multi- walled carbon nanotubes are also presented. After the discussion of nanotube/biomolecule integration onto electrode surfaces, three results are shown. The first one regards the influence on the biodetection signal of differently oriented multiwalled carbon nanotubes. Secondly, a demonstration of enhanced biodetection parameters by using multiwalled carbon nanotubes is given. Finally, a comparative study of three enzymes used to detect the same metabolite and adsorbed onto multiwalled carbon nanotubes is also reported.