Due to excellent abrasion resistance the high-chrome white irons are widely used in mining and mineral industries. Minor variation of carbon content in 28% chrome white iron resulted in difference in primarily solidified microstructure. Sub-eutectic composition led to formation of primarily solidified dendrites. Formation of primarily solidified dendrites which were supersaturated with carbon and chrome also caused precipitation of fine secondary carbides that are different from relatively large plate type M7C3 carbides in the eutectic structure. Small portion of primarily solidified dendrite expected to contribute significantly to the improvement of abrasion resistance of the white iron because the dendrites provided mechanical support to carbides. However, the volume of the primarily solidified dendrite that appeared prior to eutectic solidification of M7C3 and austenite was relatively small in the sub-eutectic white iron. HCP structure M7C3 and several carbides precipitated within dendrite arms because of supersaturated carbon and chromium in austenite. The hardness value of the high Cr white iron was high enough. Therefore, the existence of the primarily solidified dendrite did not give influence on improvement of the Charpy impact absorbed energy in sub-eutectic white iron. The relative fraction of primary dendrite increased with reduction of carbon content from the eutectic composition. The increased fraction of primary dendrite increased hardness value of the white irons. Directional solidification and quenching experiments DSC analyses revealed the difference of solidification behaviors between SubEu ( a little less carbon from eutectic composition: hypo eutectic) and EU (close to eutectic composition; eutectic or hyper eutectic) white irons. Primary austenite dendrite preferentially formed the SubEU specimen followed by eutectic reaction between austenite and M7C3 carbide. However, carbide solidification occurred before eutectic reaction in the EU specimen which is expected to be shifted to hyper eutectic composition. The primarily solidified austenite dendrite played an important role on the mechanical properties of the high chromium white iron. The primarily solidified dendrite is expected to behave as a mechanical support of the microstructure under abrasion stress.