Objective
The purpose of this study was to evaluate the difference for each variable on plain radiologic study of the foot between weighted and non-weighted routine plain anterior-posterior and lateral views in flatfoot children diagnosed by Harris mat footprint.

Method
Both feet of thirty-four children over two-year old, who had been diagnosed as flatfooted by modified Rose' classification using Harris mat footprint were included. We studied plain roentgenogram images, including anterior-posterior and lateral views, in both standing (weighted) and sitting (non weighted) position of the feet of the patients. We measured the following variables; arch height (AH), calcaneal pitch (CP), talocalcaneal angles from lateral view (TCALA) and anterior-posterior view (TCAAP), talo-first metatarsal angles from the lateral (TFML) and anterior-posterior view (TFMA).

Results
Each variable revealed no significant difference between boys and girls (p＞0.05); neither was there any significant difference noted in each parameter between the right and left feet (p＞0.05). All the variables of plain foot roentgenogram on weighted state were significantly different from the data of non-weighted state, except TCAAP (p＜0.05). CP was the only parameter which showed significant difference according to severity of flatfoot by modified Rose'classification.

Conclusion
Because most of the flatfoot in childhood is hypermobile type, it is necessary to take plain radiologic studies of the feet both in weighted and non weighted state and to compare both data of each variable. In addition, it is prefer to use plain radiologic study of foot both in weighted and non weighted state with footprint as the screening method of pediatric flatfoot lesions.