The purpose of this study was to clarify the palatal arch length, width and volume in the primary and permanent dentition. Samples were consisted of normal occlusion in the primary dentition(50 males and 50 females) and permanent dentition(43 males and 43 females). Their upper plaster casts were used and through 3-dimensional laser scanning(3D Scanner, DS4060, LDI, U.S.A.), cloud data, polygonization, section curve, loft surface and fit and horizontal plane were made for measuring the palatal arch length, width and volume(Surfacer 10.0, Imageware, U.S.A.). Correlation coefficients were calculated separately for males and females in each group(SPSS 10.0). The results were as follows : 1. Average distance from the fit plane to the points(tooth-tooth-palate) was greater in the permanent dentition than those of primary dentition. 2. Palatal volume was greater more than 3 times in the permanent dentition, especially it was greater in male compared to female with significance(p<0.05). 3. Palatal width of male was greater in the primary and permanent dentition but palatal length, only in the permanent dentition than that of female(P<0.05). 4. Correlation coefficients were statistically most significant between the palatal volume and size of posterior palatal width and total palatal length(r=0.401, r=0.450, r=0.678, r=0.654).