This book has been written to clarify the doubts of occlusal plane orientation during the fabrication of complete denture. The purpose was to assess the most appropriate point on tragus to be used as a reference point at time of marking ala tragus line while establishing occlusal plane. The data was collected in two groups of subjects- 1) Dentulous 2) Edentulous [30 {15male, 15 female}each]. Downs analysis was used for base value. Lateral cephalographs were taken for all selected subjects. Three points were marked on tragus as Superior (S), Middle (M) & Inferior (I)& were joined with ala (A) of the nose to form ala-tragus lines. The angle formed by each line (SA plane, MA plane, IA plane) with Frankfort Horizontal (FH) plane was measured by using custom made device & modified protractor in all dentulous & edentulous subjects. Also in dentulous subjects angle between Frankfort Horizontal plane and natural occlusal plane was measured.Angulations of ala-tragus line marked from inferior point with occlusal plane in dentulous subject had given the smallest value 2.46 which shows that this ala-tragus line was nearly parallel to occlusal plane.Inferior point on tragus is most appropriate.