Two novel immunosensors, one impedimetric and other one conductimetric, for atrazine detection in red wine samples have been developed. Impedimetric immunosensor is based on an array of interdigitated \i-electrodes (IDnEs) and bioreagents specifically developed to detect this pesticide. Conductimetric immunosensor incorporates additionally gold nanoparticles. Bioreagents were covalently immobilized on the surface of the electrodes (interdigital space). In both cases the biochemical determination of atrazine is possible without any redox mediator. For the case of the impedimetric immunosensor, the detection method is based on impedimetric measurements (in a wide range of frequencies), whereas in the case of the conductimetric immunosensor the detection method is based on conductimetric measurements (DC measurements).The potential of the impedimetric immunosensor to analyze atrazine in complex sample matrices, such as red wine, have been evaluated. This immunosensor can detect atrazine with limits of detection in the order sub-ppb, far below the maximum residue level (MRL) (50 \ig L"1) established by Euro ean Union (EU) for residues of this herbicide in the wine grapes.