This article describes verticsal dimension in its histologic and clinical aspect. Determination of correct vertical dimension of occlusion is one of the most important steps in prosthodontic rehabilitation. It is considered essential for improvement of facial esthetics and stomatognatic functions. Many techniques have been sued for measurement of the vertical dimension in dentulous and edentulous patients : pre-extraction record, physiologic rest position, swallowing, phonetics, esthetics, etc. But, there is no universally accepted or completely accurate method. Though a great deal of energy has been spent trying to find the exact position of the mandible, there is an controversial aspect of vetical dimension.