Fermentation of bambara groundnut (Yigna subterranea) has not been fully studied. In this project an attempt was made to ferment the beans to a dawadawa-type product using whole cotyledons in four days. Isolates from fermenting cotyledons showed Bacillus subtilis and B lichenformis as the major fermenting microorganisms. Fermentation increased the pH of the substrate from 7.0 to 8.0 after an initial fall in the first 24 h. Fermentation increased moisture, protein and fat contents of cotyledons. Total available carbohydrate reduced in 48 h to less than 50% of value at the start of fermentation but then increased to 92% on the fourth day. The increase has been attributed to secretion of slime by fermenting microorganism. Fermentation also reduced the trypsin inhibitor activity of cotyledons.