BACKGROUND: Bone age measurements have clinical significance in estimation of growth status and prediction of final adult height. Mostly used methods of bone age measurements are Tanner Whitehouse method(TW2) and Greulich-Pyle method(OP). TW2 is known to be more accurate method in determining the bone age, compared to GP. But GP is being used more widely despite some shortcomings, because TW2 is time consuming and need special training. In this study, we observed the correlation between GP and TW2 to evaluate which bone age among three portions of hand and wrist[metacarpals and phalanges(GP1), carpal bones(GP2), distai radius and ulna (GP3)], measured by GP, was more correlated with the bone age, measured by TW2. METHODS: Left hand/wrist radiographs were taken from 100 prepubertal children with normal growth. These radiogrphs were reviewed by two pediatric endocrinologists independently. Bone ages using TW2 were measured at first, and then GP1, GP2, and GP3 were measured. These bone ages had been compared with TW2, using SAS computer program. RESULTS: The mean chronological age of 100 children was 10.0+/-2.5 years(5 years to 14.7 years range, 63 males and 37 females). The bone age by TW2 was 9.0+/- 2.6 years(2.3 to 13.6 years). The bone age by GP1, GP2, and GP3 were 8.8+/-2.5 years, 8.7+/-2.9 years, and 8.3+/-2.8 years, respectively. Bone ages by TW2 were significantly closer to the chronological age than those by GP. The Pea~rson correlation coefficients of GP1, GP2, and GP3 in eomparison to TW2 were 0,87(p=0.0001), 0.94(p=0.0001), and 0.91(p=0.0001), respectively, There are significant correlatkm between bone ages by TW2 and GP. Bone ages by GP2 and GP3 were statistically significantly different from those by TW2(P<0.01). Bone ages by GP1 has no statistical difference with that by TW2(P=0.64). CONCLUSION: TW2 method is more accurate than GP method in determining the bone age, but it needs time-consuming and laborious efforts. We suggest that the use of GP method for the metacarpals and phalanges can result in a considerable saving of time with no significant loss of accuracy and reproducibility.