Technical Abstract: Using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry, we investigated the distribution of the low abundant proteins that are involved in soybean seed development in four wild and twelve cultivated soybean genotypes. We found proteomic variation of these proteins within and between the two groups. The majority of the variation among these sixteen genotypes was observed in the seed maturation proteins, which consisted of 4-6 protein spots. All genotypes showed 3 spots of sucrose-binding protein except one wild genotype which had 2 spots. Two protein spots were detected for a triacylglycerol (TAG) accumulation factor protein in thirteen genotypes, while one spot was detected in one ancestral and one wild genotype, and no spot was detected in one of the wild genotypes. All genotypes showed 3 spots of alcohol dehydrogenase except one Asian landrace and one wild genotype that had only one spot. Minor proteomic variation was detected in sixteen genotypes for an elongation factor (EF2) and formate dehydrogenase, with apparent absence of this protein in one wild genotype. No differences in the proteomic distribution of dehydrin-like protein, seed biotin-containing protein, glyceraldehyde 3-phosphate dehydrogenase, and fructose bisphosphate aldolase were detected.