Soybeans and non-fermented soyfoods, including soymilk, contain only 5 to 10% of total isoflavone in a biologically active aglycone configuration, with the remainder found as isoflavone glucoside conjugates. Saccharolytic enzyme-producing Bifidobacterium, classified as probiotics, are commonly incorporated into fermented milk products to enhance their health benefit. Postmenopausal women, who are associated with high rates of chronic disease due to ovarian failure and subsequent diminishing oestrogen levels, are seeking natural alternatives to oestrogen and hormone replacement therapy due to its proposed adverse cancer-related effects. The main objectives of this study were to develop an isoflavone aglycone-enriched fermented soymilk containing viable bifidobacteria and examine the effects of ingesting this product on the bioavailability of isoflavone and markers of disease risk in postmenopausal women.