Abstract
Mutants with changes of seed protein content in rice were obtained by ethyleneimine (EI) treatment with three levels of concentration. In M2 generation mutation frequency and nurnber of high protein mutants increased with the increasing EI concentration. Agronomic characteristics of some mutants with high protein content were also observed in M4 generation. The characters of most of them were improved or at least sirnilar to those of the original variety. These facts seem to suggest the possibility of breeding new varieties with high protein content of grain by utilization of EI induced mutants.