The intention of this study was. ti examine the delopmental trend of conceptions of right and left in Korean children. The subjects for the study included 370 children at 4 to 12 years of age through random sampling. The instruments used in this study were six tests with 24 items employed by Piaget. Ss were individully interviewed. The data obtained from these tests were analysed by percentages which were passed frequencies for the each item. The results obtained from this study were concluded as follows : 1) The development of conceptions of right and left increased with the increasing age. Children at 5 to 7 years of age showed right and left from their own point of view. That is, they identified the others`right and left as mirror images of their own right and left as mirror images of their own right and left. At 8 and 9 years of age, children could identify right and left the standpoint of other person. From 10 years of age, these relations were viewed from the standpoint of objects. 2) Sex was not significant variable which could predict the developmental stages of conceptions of right and left. 3) On the basis of our results, the developmental stages of conceptions of right and left can be formulated as follows, different from that of Piaget: First stage : 5 to 7 years of age Second stage : 8 to 9 years of age Third stage : after 10 years of age For the future task, it can be recommended that the systematic study, particularly in accordance with the socio-economic status, should be carried out in this field.