Abstract: This study was conducted to evaluate the effect of mixed cultures on the nutritional and antinutritional content of combined fermented jack beans. The combined role played by individually selected microorganisms (bacteria and fungi) involved in the natural fermentation of jack beans, under controlled environment was investigated. One hundred gramme of ground, samples were inoculated with the mixed cultures under aseptic condition using 1 mL of each inoculum and fermentation allowed to take place under controlled environment of temperature of 40°C for the liquid state fermentation (with bacteria being the inoculum) for 7 days. Thereafter the fungi were inoculated aseptically for the commencement of the solid state phase of the combined fermentation for another 7 days at the temperature of 30°C. The inocula range between 3-7 species in number. Physical sensory changes, fermentation parameters, proximate and antinutritional composition were determined during fermentation. The total titratable acidity values of the multiple starter culture fermenting substrates increased from 0.04-0.43%. While the pH values decreased from 6.5 to 4.3. The higher the number of species used as inoculums, the more acceptable the fermented samples (in terms of sensory properties). Irrespective of the number of species used in the fermentation, there was a significant increase in the crude protein from 26.20-39.82 g/100 g, while the fat (11.95-4.33 g/00 g) and ash content (3.50-2.23 g/100 g) shows a decrease in comparison with the control. The mineral composition showed a significant increase in magnesium (30.07 to 46.77 mg g-1), sodium (18.51 to 34.34 mg g-1), potassium (23.51 to 40.88 mg g-1) and iron (0.00 to 0.08 mg g-1) when compared with the control. Of all the antinutrient content analysed, only phytate (58.66 to 5.08 g/100 g) and canavanine (0.79 to 0.40 mg g-1) has significant decrease in comparison with the control. Hence, it can be deduce from this work that the use of multiple starter culture in combined fermentation can be used to improve the nutritional content of Canavalia ensiformis L.