Esterase isozymes in the leaf blade were observed in the $F_2$ populations derived from the cross combination between a japonicaindica hybrid rice variety with EIZ 1 ($EST_1,;EST^S_2,;EST^F_3$) and a japonica rice variety with EIZ 6 ($EST_1,;EST^O_2,;EST^S_3$). The esterase isozyme of the 6A ($EST^S_2$) band was controlled by a dominant allele, while the esterase isozymes of 12A ($EST^S_3$) and 13A ($EST^F_3$) bands were controlled by codominant alleles. No linkage relation was indicated while between $EST_2$, and $EST_3$. The presence of esterase isozyme of 13A ($EST^F_3$) band is related to the grain shedding habit and esterase isozyme of 13A ($EST^F_3$) band itself is somewhat related to the cracking characteristics of the abscission layer. The presence of esterase isozyme of 6A ($EST^S_2$) band is related the days to heading and it might due to the panicle length and ratio of fertility. There was no difference in the plant height, culm length, and number of tillers per hill between EIZ in the $F_2$ population. Therefore, there were the relationships between esterase isozymes and some agronomic traits in rice plants.