The aim of this study was to identify and compare bone age assessments of Turkish children in regions of Central Anatolia and Eastern Anatolia using the Greulich-Pyle (GP) method. Evaluation was made of 849 (375 boys, 514 girls) adolescents aged between 9 and 17years, who lived in two geographically different regions of Turkey. The selection criteria included normal growth and development, a state of good physical and mental health with no previous history of chronic or acute illnesses, no past trauma or injury to the hand-wrist region, no congenital or acquired malformations of the hand-wrist area, no hormonal disorders, and good quality hand-wrist radiographs. Bone age (BA) was evaluated using the GP method from definitive radiographs of the left hand-wrist. The total mean differences between BA and chronological age (CA) for girls and boys were found to be 1.19 +/- 1.2 (p<0.05) and 0.90 +/- 1.2 (p<0.05) years in the Eastern Anatolia region and 0.28 +/- 0.6 (p>0.05) and -0.10 +/- 0.3 (p>0.05) years in the Central Anatolia region. There were significant differences between BA and CA in all age groups for girls and boys in Malatya (a city in the Eastern Anatolia region) and in 10 and 13year olds for girls and 12, 13, 15, and 16year olds for boys in Sivas (a city in the Central Anatolia region). Statistically significant differences were determined between the BA and CA of the subjects living in Malatya and Sivas (p<0.05). The results of this study using the Greulich-Pyle atlas indicate that bone development is completed earlier in adolescents living in Malatya compared with those in Sivas.