Abstract: Microorganisms associated with fermented cheese whey were isolated and identified. Four different bacteria; Bacillus brevis, Lactobacillus acidophilus, Micrococcus lactis and Pediococcus cerevisiae were isolated. These bacteria were then tested against diarrhea -causing organisms; Bacillus cereus, Enterobacter faecium, Escherichia coli NCTC 10418, E. coli ETEC, Salmonella enteritidis, Salmonella paratyphi A, Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus. Micrococcus lactis inhibited all the test organisms with zones of inhibition from 7.0-24.0mm diameter, unlike the other isolates which inhibited few of the test organisms. The inhibition mediated by M. lactis was also superior to most of the antibiotics used except cephorex and oflomed which ranged from 8.0-27.0 mm and 1.0-36.0 mm, respectively. It is therefore being suggested that in the absence of antibiotics, fermented cheese whey can be used to treat diarrhea especially in rural areas where there may not be quick access to convectional antibiotics.