In the present study, lateral cephalometric head films of 60 subjects, 30 males and 30 females, were used. The films were taken at natural head position. The subjects had different vertical facial development, and their age range was 13-15 years. The sample was divided into two groups, neutral and clockwise, according to Jarabak ratio, and each of them was also divided into two subgroups according to sex. The effects of vertical development and sex on the natural head position and hyoid bone location were investigated by variance analysis. As a conclusion, it has been found that NSL/OPT and ML/ VER of the postural measurements and only Hy-Pog of the measurements regarding the hyoid bone location were statistically different between neutral and clockwise groups. In addition, it has been observed that the postural measurements were not affected by sex, while only Hy⊥SN-S measurement concerning the hyoid bone was.

Keywords: Vertical facial development, Natural head position, Hyoid bone