Protein is one of the major factors in rice quality. The study on inheritance of protein content is to play an important role in rice breeding for high protein. In this research, the analysis of inheritance of protein content were canied out at the rice varieties such as: Khang Dan 18 (KD18), Q5 (the rice varieties with low protein content) and the rice varieties: P290, PG, P4, P1, AC5 (the rice varieties with high protein content). The results indicated that the protein content in rice seed maiIy controled by genetic factor/gene (s). The gene (s) controled the protein content are partly dominant and having additive inheritance. The cytoplasm inheritance may contribute to the protein content in rice seed. The progenies of cross combinations fully had none amine acides which inherited from their parents and the amine acids in the progenies are higher than their parent.