An electrochemical immunosensor based on patterned plasma-functionalized multiwalled carbon nanotubes (pf-MWCNTs) working electrode for Legionella pneumophila detection is described in this paper. Polyclonal antibody was immobilized using passive adsorption and covalent immobilization on the surface of the pf-MWCNTs. Various dilutions of Legionella 19-kDa peptidoglycan-associated lipoprotein (PAL) were added onto the electrode surface and incubated. The assay was then completed using polyclonal antibody conjugated to horseradish peroxidase (HRP) as the enzyme label. 3,3',5,5'-Tetramethylbenzidine dihydrochloride (TMB)/substrate solution (H2O2) was used as the mediator/substrate system. Electrochemical detection was conducted using cyclic voltammetric at 500 mV versus silver/silver chloride (Ag/AgCl) reference electrode. L pneumophila detection of 0.16 ng ml(-1) and similar to 0.0025 ng ml(-1) was achieved respectively for passive adsorption and covalent immobilization. (C) 2010 Elsevier B.V. All rights reserved.