The effects of the pre-treatment of low temperature on the expression of chlorosis were examined during the leaf growth process in rice plants. 1. When the base of shoot was pre-treated by low temperature, the second leaf emerged after the pre-treatment showed chlorosis, although the other plant parts were exposed under high temperature. The expression of chlorosis may be caused by the low temperature sensitivity of leaf primordium (ca.1mm) enclosed in the shoot base. 2. The transferring from high to low temperature (15°C) induced the chlorosis in the second leaf emerged after treatment, while the change from low to high temperature (25°C) formed normally the chlorophyll in the third leaf emerged after the treatment.