Flour and starch were prepared from six Thai banana cultivars: Kluai Hom, Kluai Khai,Kluai Lebmuenang, Kluai Namwa, Kluai Hakmuk and Kluai Hin, and their resistant starch (RS), invitro starch digestibility and physico-chemical properties were determined. The RS content of theflour is 52.2-68.1%, with flour from Kluai Hin containing the highest amount of RS, followed by thatfrom Kluai Hakmuk. The starch has a higher RS content (70.1-79.2%), the highest value comingfrom Kluai Hakmuk starch, followed by Kluai Hom starch. A significant linear relationship betweenapparent amylose and RS was observed. Interestingly, most of the flour showed a slower rate of invitro starch digestibility than that of the starch, with Kluai Hin flour exhibiting the slowest rate,followed by Kluai Namwa. Rapid viscosity analysis showed significantly higher peak viscosity of thestarch than the flour, the highest final and setback viscosity being obtained from Kluai Hin starch.Differential scanning calorimetry showed an endothermic transition enthalpy over a range of 17.4 J/gfor Kluai Lebmuenang starch to 18.6 J/g for Kluai Hin starch. X-ray diffractograms of the starchesexhibited a typical B-pattern with Kluai Hin showing the highest degree of relative crystallinity(31.3%) with a sharp peak at 5.5 . The overall results seemed to indicate an effect of the BBgenotype on the resistance of banana starch granules to enzymatic digestion due to amylosemolecules and the crystallinity of amylopectin.