In order to compare the iron concentrations of the marketed ferruginous hematinics with the sustained-releasedosage forms and to prepare the good hemantinic which can be absorbed effectively without forming "iron block" in the gastrointestinal tract, gelatinized micropellets containing medicament were prepared and hardened in 10% formalin-isopropanol in the time of 72 hours. These micropellets were digested with artificial gastric juice and plotted a curve of released iron concentration. As a result, it is found that gelatinized micropellets sustained-release dosage form is an excellent ferruginous hemantinic and it is shown that several marketed preparations can be improved in their hemantinic actions by forming the sustained-release dosage.se dosage.