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In this thesis the microbial populations in ready meals, prepared with the method cook and chill, were studied experimentally. Specifically, the categories of microorganisms that were studied were aerobic mesophilic microorganisms, enterobacteria, lactic acid bacteria and yeasts and moulds. Statistical programs were used to determine whether there is a dependency relationship between the microbial populations and the days of cold storage and to cluster the meals on the basis of their behavior in relation to these two variables. The analysis of the results showed that there is a dependency relationship between the two variables and specifically as the days of cold storage of ready meals increase, the presence of microbial load is also increased. The ready meals were clustered on the basis of the changes in microbial populations on each measurement day. For aerobic microorganisms four different clusters were created, for lactic acid bacteria three clusters, and three for yeasts and moulds. The product MEAT SOUP constituted a cluster by itself, that with the largest increases in lactic acid bacteria and yeasts and moulds. In this study some cook and chill ready meals, such as MEAT SOUP and SPAGHETTI WITH MINCED MEAT, were found to have particularly high populations of microorganisms. Numbers of microorgansisms in theready meals were plotted on a straight-line slope (b), which determines the growth rate of the microbial population with storage time. Ready meals with seafood exhibit a high rate of growth (high beta values), while BARLEY PASTA and ready meals with potato as basic ingredient have a low rate of increase in microbial load.