Cyclodextrins are very useful compounds for the food, cosmetic, pharmaceutic, and plastic industries. We developed a process for the production of cyclodextrins from moderately heat-treated cornstarch. This method had many merits. First, the cyclodextrins were not degraded by cyclodextrin glucanotransferase, because low molecular weight maltodextrins were hardly produced. Second, it was possible to remove the residual cornstarch by a simple method such as filtration or centrifugation. Third, the amount of cyclodextrin glucanotransferase used for cyclodextrin production was less than that using the traditional method. Fourth, the pretreating method was simple. And fifth, the residual starch could be used as substrate for the production of other compounds. Cyclodextrins were produced at optimum conditions : heating temperature was 65 degrees C; heating time was 1 h; concentration of substrate was 7.5%; amount of enzyme loaded was 48 U g(-1) of substrate. Using these conditions, the results were as follows : the content of cyclodextrins, 50%; the conversion yield of substrate, 25%; the productivity per enzyme unit, 5.22 mg of cyclodextrins.