In this paper, a real time recording system for the Brainstem Auditory Evoked Response (BAER), designed and developed is evaluated by testing the known effects of click polarity on interpeak latencies (IPL) of BAER in normals and in patients with suspected Brainstem Ischaemia. The click polarity affects IPLs. The Rarefaction click generates the clearest waveform which would be most useful in clinical diagnosis.