Using a previously pre-tested structured questionnaire, the traditional processing method for kirario (a traditional fermented porridge of the Merus in Kenya) was studied and documented. The biochemical and microbial profile changes during fermentation of kirario, both by the traditional method and in the laboratory were monitored for 48 hours. Samples of kirario from ten localities in the study region were analyzed. Samples of the final products from the traditional method were analyzed for total viable counts (TVC), lactic acid bacteria (LAB), lactococci, yeasts
and moulds and coliforms, while the laboratory samples were taken at six (6)-hour intervals and analyzed for TVC, LAB, lactococci, and yeasts and moulds for 48 hours. The traditional product showed average TVC, LAB, lactococci, yeasts and moulds of 9.30, 9.63, 8.62, and 4.83 log10 cfu/ml, respectively. Coliform counts were detected in only two of the samples at