It has been claimed that the ANB angle is affected by several environmental factors and thus a diagnosis based on this angle may give false results.  By arbitrarily varying the position of points, lines and angles on cephalometric drawings, some authors have demonstrated geometrically that ANB angle can be changed, although the intermaxillary relationship were unchanged. So , the aim of the study was to evaluate effect of change in position of landmarks on qauantification of sagittal jaw parameters. Material and Methods: There were total of 100 lateral cephalograms used for the study out of which 35 cephalograms were of male patients and 65 cephalograms were of female patients. Lateral cephalograms were taken from the pretreatment record files of the patients. The study sample was divided into 3 groups based on their skeletal relationship. Results: A 1.50 increase in angle ANB with every 4.0mm decrease in SN length and vice versa was observed. Each 50 increase in SN-OP caused 3.5mm decrease in value of Wits appraisal.  Each 5.00 decrease in SN-OP resulted in a 3.5mm increase in value of Wits appraisal. Each 4.00 increase in SN-PP caused 3.0mm decrease in value of App-Bpp.  Each 4.00 decrease in SN-PP resulted in a 3.0mm increase in value of App-Bpp. Conclusion: From the current study it can be concluded that, THE CHANGE OF Position of landmarks had a effect on the quantification of sagittal jaw parameters.
Key words: Cephalometrics, sagittal jaw parameters.