Technical Abstract: Soybean variety exhibiting at maturity, normal (NM), low-linolenic (LL) or low-saturate (LS) fatty acid seed oil composition had starch structure and functional properties studied from seeds collected 20 days prior to harvest. Soybean starch had small granules (0.4-4.5 micrometers diameter), and CB-type crystallinity. LL and LS soybean starch had significantly lower absolute amylose than NM soybean. Weight-average amylopectin molecular weight, measured by HPSEC equipped with multi-angle laser-light scattering and refractive index, ranged from 5.91 x 108 g/mol for LL to 8.92 x 108 g/mol for NM, but no significant differences observed. Amylopectin branch chain-length distribution, measured by HPAEC equipped with amyloglucosidase post-column and pulsed amperometric detector, showed soybeans had short average chain-length (DP 19.9-21.9) and LS soybeans had significantly higher percentage of DP 6-12 than LL and NM soybeans. No significant differences among soybean varieties were observed for starch thermal and pasting properties, with onset gelatinization temperature (51.0 degrees C-51.8 degrees C) and peak viscosity (79-100 RVU) both low. High variability in starch characteristics were observed among field replicates, with more differences likely to be observed once variation sources are understood. Further research would be worthwhile to establish if amylose content or amylopectin fine structure of developing soybean seeds influences fatty acid oil composition at maturity.