Sheets consisted of entire single-walled carbon nanotubes (SWNTs) were used as the working electrode for electrochemical measurement of ethidium bromide by covering a glassy carbon electrode (GCE) using the SWNT-sheet. This SWNT-sheet based electrode exhibited a fast electron transfer process on the electrode surface via the cyclic voltammetry with K4Fe(CN)(6) as electrochemical probes. This SWNT-sheet based electrode showed also a high sensitivity toward ethidium bromide, a typically harmful, aromatic backboned chemical. The SWNT-sheet based electrode was capable of accumulating ethidium bromide to a higher concentration and therefore was capable of detecting ethidium bromide with a detection limit of 1.0 x 10(-8) M. (c) 2009 Elsevier B.V. All rights reserved.