A multi-electrode lead (10) comprises an elongate carrier (12) having a longitudinal axis. A plurality of electrical conductors is carried by the carrier (12), a plurality of electrodes being connected in spaced relationship to each conductor. The electrodes (14) are arranged at axially spaced intervals along the carrier (12) so that, along the length of the carrier (12) electrode (14) associated with any one of the conductors only once has an electrode (14) associated with another one of the conduct adjacent to that any one electrode (14). In another aspect of the invention, an ablating device (50) comprises an elongate tubular sleeve (52) for effecting spot ablation of tissue, a sensing electrode catheter being receivable in the passage (54) of the sleeve for assisting in positioning of the ablating electrode (56), in use Preferably, the sensing electrode catheter is the multi-electrode lead (10) of the first aspect of the invention.