Loading and release characteristics of insulin-carrying albumin and starch microspheres have been studied in vitro. The sorption characteristics of 125I-labelled insulin onto albumin microspheres were studied and were found to be completed within 5h, and the loading capacity was found to be 0.14% w/w. Insulin did not show any sorption into the matrix of the starch microspheres. The release characteristics were analyzed by high performance liquid chromatography. About 80% was released within 5-10 min from albumin microspheres and starch microspheres, respectively.