The purpose of the present study was to determine the standard mesiodistal' diameter and bucolingual diameter of the crown size and the dental arch size in the primary and permanent dentition of Indonesian-Jakarta children. The samples were obtained from dental plaster models of 400 Indonesian-Jakarta children who were selected from a cross section of the population and who ranged in age from 3 1/2 years to 6 1/2 years and from 10 I/2 years to 13 I/2 years. The mean values of the mesiodistal and bucolingual diameter of primary dentition are found tended to be larger in boys than in girls. The mean values of the mesiodistal and bucolingual diameter of permanent dentition are found tended to be larger in boys than in girls. Also for mean values of the dental arch width and length of primary and permanent dentition are found tended to be larger in boys than in girls.