Auditory brainstem response (ABR) is widely used in ENT to investigate hearing loss. This test evaluates the response of the ascending auditory pathway, from cochlea to mesencephalon, following auditory stimulation. It provides precise analysis of waves numbered I to V according to location on the auditory pathway, in terms of amplitude, latency and inter-wave interval. Good-quality assessment requires familiarity with the parameters to be used and the factors likely to modify response. We describe the procedure for ABR examination and the recorded responses, with particular attention to factors influencing response to which the examiner must be vigilant. These factors are related to the individual (age, gender, hearing loss, body temperature, drug treatments), transducer (air or bone conduction), stimulation parameters (type, polarity, intensity, calibration, duration, cadence, number of clicks, background noise) and acquisition parameters (analysis window, scale, electrodes). We also briefly describe the clinical applications of this examination.