In this paper a new electrochemical method for direct immunodetection in real time is presented. The method is based on measurement of the impedimetric variations due to interaction with antigens on platinum electrodes functionalized with polymeric layers containing antibodies. In contrast to a classical impedimetric method, our method allows a differential mode of measurement, ensuring the specificity of the signal. The set-up includes a flow injection system, which is a convenient method of changing solutions and displaying the effect of the different parameters on the resulting responses.