Objective
This study was aimed to demonstrate definite diagnostic radiologic criteria between normal and flatfoot.

Method
Sixty healthy subjects and fifty two flatfoot cases were evaluated by radiologic measurements. We evaluated criteria for longitudinal arch curve by measuring of calcaneal pitch, talocalcaneal angle, talometatarsal angle, metatarsal angle and navicular height I and II.

Results
Over 10 years old, there was significant correlation between normal group and flatfoot in calcaneal pitch, talocacaneal angle, difference angle, metatarsal angle, navicular height I and II. But below 10 years old, there was difference in only talometatarsal angle and metatarsal angle. Therefore talometatarsal angle and metartarsal angle are valuable in diagnosis of flatfoot in all age group.

Conclusion
In diagnosis of flatfoot, variable radiologic measurement are clinically significant.