The characteristics (chemical, microbiological and organoleptic) of commercial fresh and mature Halloumi cheeses were examined. In addition, the effect of the feeding regime of lactating animals on the flavour of fresh Halloumi cheeses was also assessed. Three different brands of Halloumi cheese (industrial, Traditional 1 and Traditional 2), based on milk origin and location of the dairies, were selected for subsequent analysis. The industrial cheese was made with bovine milk as the major ingredient (an insignificant mixture of ovine/caprine milk might be included), while the traditional cheeses were primarily manufactured with ovine milk (a small amount of caprine milk might be included). The traditional cheeses also differed in the location of the dairies, in that Traditional 1 cheese was manufactured in the province of Paphos while Traditional 2 cheese was made in Nicosia province. Differences were revealed both between the types of cheese and age, i.e. fresh versus mature. The characteristics that differed included the microbiological load of fresh samples, the type and quantity of flavour compounds, and the rate of proteolysis. Some of the volatile compounds present in Traditional 1 cheese probably originated from plants present in the grazing plains (thyme and burnet), while the mint added during manufacture contributed, almost exclusively, to the plant volatile compounds that were present in Traditional 2 cheese. The sensory analysis identified significant differences between the three brands. Moreover, the panels (young and older) assessed the cheeses in a different way, reflecting a probable effect of panel age on sensory testing. During the microbiological analysis of the mature traditional Halloumi cheeses a new Lactobacillus species was recovered, which was named Lactobacillus cypricasei. In order to improve the organoleptic characteristics of bovine Halloumi cheese, two 'natural starter cultures' were isolated from raw milks and incorporated into bovine milk for the manufacture of cheese in the laboratory. One selected starter culture, Lactobacillus rhamnosus, was used to ripen the bovine milk prior to Halloumi cheese manufacture, but its activity failed to bring about the anticipated results. The degradation of protein and fat was monitored throughout the maturation of the cheese, and only minor differences were observed between 'experimental' (starter culture) and 'control' (no starter culture) Halloumi cheeses. The sensory analysis of fresh and mature Halloumi cheeses reflected the results of the instrumental analysis, for the panel did not detect any significant differences between 'experimental' and 'control' cheeses. In the light of the high frequency of occurrence of Enterococcus faecium in the fresh samples of traditional commercial samples and ovine milks, it was decided to assess the survival of the micro-organism under normal cheesemaking conditions. Hence, Halloumi cheese with a starter culture of E. faecium was produced in the laboratory. The results showed that some cells of E. faecium survived the harsh cooking treatment (90°CI 1 h) of the cheese blocks during Halloumi cheese manufacture. The experiments were not completed due to the controversy about using Enterococcus spp. in cheesemaking. Overall, the analysis of commercial and laboratory cheeses has given an insight into the special characteristics of Halloumi cheese, and provided with a better understanding of how flavour and texture develops with cheese maturation.