Chemical modified corn starch (CMS) such as; starch acetate  (SA), starch succinate  (SS) and starch phosphate (SP) were prepared, and their chemical, functional properties and biological effects were evaluated. Protein, fat and ash contents of corn starch were decreased by the modification process, except the ash content was  increased  in SP. Also, the amylose content was decreased in both SA and  SP, while it was  increased in SS. For functional properties, the obtained results showed that water absorption capacity (WAC) at 25°C and solubility at 90°C were increased in all CMS. Meanwhile, the viscosity was decreased in  both SA and SP while, it was increased in SS. Swelling power at 90°C was decreased only in SP . Biological experiment was conducted on normal albino rats after feeding on diet  containing 10% of modified starch, the result showed that feeding on both SA and SS decreased the final body weight , while feeding on diet  containing  SP caused slight increase in final body weight. The experiment on diabetic rats showed a significant  decrease in body weight compared with normal rats. Also, feeding on SA significantly decreased serum glucose of healthy and diabetic rats . However , feeding on CMS had no significant differences on lipid fractions, kidney  functions and liver functions on healthy  rats compared with diabetic rats.