Subsequent to a critical consideration of the ambiguous methods of evaluation and documentation of electronystagmograms (ENG) practised up to now, in particular the butterfly-scheme and the L-scheme, a method is being introduced unequivocally describing the vestibular reaction, on the basis of primary nystagmus functions. Deducted from the theory of rotary nystagmus, this procedure may be transferred to any other experimental vestibular test - taking the knowledge of the primary nystagmus relations for granted - and any ENG registered correspondingly may be documented in the form as described above, and may be reproduced in an idealized state any time. Thus the goal of a documentation in electro-nystagmography, i.e. the most comprehensible recording possible of the information contents of a registered nystagmus, is widely reached. There still remains to insert the speed of the quick phase into the evaluation scheme.