The important base of orthodontic treatment is correct diagnosis . One of the diagnostic tools is lateral cephalogram. There are some differences in normal standards between different races. The present study was carried out with the aim of determining and assessing the cephalometric standards of boys with the age of 17 to 20 years old in Hamadan.

Among 1204 boys of preuniversity centers , 27 persons were selected based on IOTN and normal occlusal standards. Lateral cephalograms were obtained in  Natural Head Position. 22 cephalometric variables (15 angles , 5 lines , 2 ratios )
   were determined and measured three times by an orthodontist . Student t - test used for analysis.

Mean age of the cases were 18.2±1.4 years. Range of reliability coefficient was between 0.901 to 0.986. In comparison with similar studies following variables were statistically different at p<0.05 level: Articular  Angle= 146 ,Gonial Angle =118 , NPog-TH =89 , AB-TH = 4.6 , L1 –TH =116 , Go Gn –TH =20 , Ant. Cranial se =76mm.

The length of anterior cranial base in our study was significantly less than Michigan standards and there was a tendency to more traight profile in this evaluation . In comparison with the Cooke standards there was less  protrusion in mandibular incisors and more counter-clockwise rotation of mandible. In comparison with similar study on girls(with normal occlusion and 18.2±1.1 years old)
   linear measurements were generally greater in boys. Therefore it is important to consider the ethnic and racial variations in our ideal treatment plan.