Potato starch was rendered digestion resistant by the addition of fatty acids (lauric, myristic, palmitic, stearic, oleic, or linoleic) and heat treatment. The effect of different fatty acids on starch digestibility was investigated, as well as the relationship between digestibility and the quantity of fatty acids able to form starch complexes. Although myristic acid reduced digestibility by the greatest degree in samples adjusted to 15% moisture content, no significant difference (p＜0.05) among fatty acid types was observed in samples adjusted to 20% moisture content. Digestibility tended to decrease with increasing internal free fatty acid (IFFA) content up to 4 mg per 1 g of starch (dry basis) but did not change substantially for IFFA content greater than 4 mg. This result suggests that starch-fatty acid complex formation reaches saturation when IFFA content is approximately 4 mg and that further addition of fatty acid has no remarkable effect on digestibility.