Technical Abstract: The primary goal of this research was to use an in vitro digestion/Caco-2 model to study iron bioavailability in 8 bean genotypes (three Mesoamerican and five Andean) that represent diversity of grain types in the crop. Complementing this goal, we measured the distribution of both iron and phytate in different bean grain tissues (cotyledon, seed coats and embryos). Bioavailability tests were conducted on cooked, lyophilized and ground beans grains with or without seed coats. The cotyledons represented 88-92% of the grain weight, and their iron concentration ranged from 45-83 ug/g while the seed coats represented between 8-10% of grain weight and their iron concentration ranged from 28-156 ug/g. The embryo represented the smallest fraction of the entire grain weight 0.64-1.82% but their iron concentration was among the highest 88-146 ug/g. In whole bean grains, iron concentration ranged from 48-74 ug/g and was similar to previous reports for some of the genotypes. Phytate concentration (measured as umols phytate g-1) was found to be higher in the embryo than in the seed coat or cotyledons but at most represented only 3% of the total phytate in the grain. Seed coats were confirmed to be the exclusive tissue containing polyphenols; thus, the removal of seed coat improved iron bioavailability from the bean samples from an overall mean response of 3.7 to 20.3 ng ferritin/mg protein. The highest Caco-2 cell iron uptake was observed from the genotypes G19833 and Radical Cerinza, which were also the genotypes with the highest cotyledon iron concentration. These results suggest that iron accumulation varies among bean genotypes and confirmed the importance of polyphenols compared to phytates in their influence on iron bioavailability to Caco-2 cells.