Amylose content and amylographic viscosity measurements, both chemical and physical properties of milled rice, arc important eating and processing quality parameters and are characteristics of a endosperm. A six-parent diallel cross was made and, thus, a genetic study on such endosperm characteristics was conducted. Since amylose contern and amylographic viscosity measurements are difficult to be determined on a single grain basis, samples of bulking heterozygous F2 grains from combining homogeneous heterozygous F1 plants were used as measurement units. Results of Griffing's and Hayman's diallel analyses of variance for the parameters, amylose content and amylographic peak, hot-paste, cool-paste breakdown, setback and consistency viscosities, are respectively presented. It was evident that gene action in the parents studied was mainly additive for all evaluated endosperm characteristics, although dominance effects were also involved. The fact that reciprocal differences in both Griffing's and Hayman's diallel analyses were not significant indicated that Hayman's assumption (2) no differences between reciprocal crosses was met in this study. Date indicated that significant dominance gene effects wer due to a directional dominance effect, an asymmetry of the gene distribution, and a residual dominance effect for all studied quality parameters except for hot-paste viscosity, in which the effect of an asymmetry of the gene distribution was not significant.