Eight healthy adults with no prior history of kidney stones participated in eight oxalate (Ox) load tests, seven foods, and an Ox solution control. After correction for endogenous Ox synthesis, increases in urinary Ox excretion during the 8 hours after eating one meal of the two soybean lines and five soyfoods tested ranged from 19.6 ± 23.3 to 124 ± 156 mmol (1.7 ± 2.1 to 10.9 ± 13.8 mg). Thus, frequent consumption of soybeans and soy products (TVP, soynuts, soy beverage, and tofu) may be a risk factor for CaOx kidney stone formation in susceptible individuals, such as those with a prior history of Ca stones, high normal urinary Ox concentrations, or intestinal disease.