The variations of the anther and pistil length of some rice cultivars at the different planting density and fertility levels were tested and their inheritance mode was studied. The anther length of a spikelet on a secondary panicle branch was longer than the one of a spikelet on a primary panicle branch. In the cultivar Z97B, both the anther and the pistil length were increased slightly along the increased plant-ing spacings, But, in the cultivar IR43 no general tendency was observed. The fertilizer levels applied n the field did not affect both the anther and pistil length of a given cultivar. In a cross of IR56/IR8, the anther length showed continuous variation with longer anther being recessive in the F2 population. While, the pistil length showed a continuous variation with longer pistil being over-dominance. In all of the crosses which IR56 involved, the general and specific combining abilities were high for both the anther and pistil length. The broad sense heritability for anther length was 0.46, and for pistil length was 0.88. The correlation coefficients of anther length and pistil length were 0.33 for phenotypic and 0.44 for geno-typic.