The important micro-organisms of 'ogi' fermentation have been enumerated, isolated and identified. The moulds isolated consist of Cephalosporium, Fusarium, Aspergillus and Penicillium. Of the aerobic bacteria, only Corynebacterium and Aerobacter could be identified. Lactic acid bacteria present were found to be mainly Lactobacillus plantarurn. There were also yeasts of which Candida mycoderma, Saccharomyces cerevisiae and Rhodotorula were identified.There was indication that. Corynebacterium hydrolysed the starch of maize to form organic acids. Aerobacter cloacae was shown to be capable of increasing the riboflavin and niacin content of the mash, while L . plantarum was mainly responsible for the production of lactic acid, the main flavour base of ogi. Saccharomyces cerevisiae and Candida mycoderma were also found to contribute to flavour acceptability.