ABSTRACT –A major aim of this study was to determine the diagnostic value of 4 electrophysiological tests in MS, and particularly their effectiveness in detecting signs of brainstem involvement. Therefore, auditory brainstem evoked response (ABER), somatosensory evoked response (SSER), blink reflex and electronystagmographic (ENG) investigative methods were applied to a group of 89 patients with definite, probable or possible multiple sclerosis (MS).The 4 methods yielded interdependent data, especially where the brainstem function was concerned, thus it can be concluded that a single demyelinating lesion may cause a combination of electrophysiological disorders within a small structure such as the brainstem.ENG recordings were found to reveal the highest number of asymptomatic abnormalities. The combination of ABER and ENG tests revealed electrophysiological disorders in 81% of all patients. The blink reflex and the SSER tests gave hardly supplementary informatio