A disposable voltammetric sensor for the detection of DNA sequences specific of Legionella pneumophila is presented. The sensor is based on a sandwich-hybridization format assay, using a stem-loop DNA structure as capture probe immobilized onto a screen-printed gold electrode. The signaling-DNA probe is labeled with biotin, and streptavidin-alkaline phosphatase is used as reporter molecule. 1-Naphthol, the enzymatic hydrolysis product of α-naphthyl phosphate, is voltammetrically detected. The hairpin-modified screen-printed gold electrode allows the detection of a 52-mer DNA sequence at 400 pM level. With a sample volume of 40 μL, this concentration corresponds to ca. 16 fmol of a DNA sequence specific of L. pneumophila. The analytical performance of this platform is compared with that previously obtained for a sensor constructed on a conventional disk gold electrode with the same geometry (Ø=1.6 mm) and design. A lower quantification limit is obtained with the SPE. In addition, the selectivity is improved as the disposable device shows a better discrimination between L. pneumophila and L. longbeachae or L. micdadei under identical nonstringent conditions.