Diamond wire cutting machines have been used in marble industry since 1985 and have affected the production rate and efficiency considerably. Despite the common use of these machines in our country, there is a lack of investigation about improvement of working conditions together with increasing efficiency. The cutting angle of diamond wire and wearing at the diamond beads are some of the operating parameters of diamond wire cutting machines. A study related to determination of optimum operating conditions will increase the rate of production, enable the proper selection of diamond wire type and efficiency of cutting. In the scope of this study, concerned with the mentioned problems, diamond wire cutting studies in industrial scale were performed on rocks with different mechanical and physical characteristics in seven different marble quarries located at Ankara-Cubuk, Usak-Banaz, Eskisehir-Sivrihisar, Mugla-Milas, Mugla-Kozagac, Afyon-Iscehisar and Burdur-Yesilova and data were collected without changing operating condition of quarries. During data collection and diamond wire cutting, some of the machine and cutting parameters are fixed so that some of the effective parameters in cutting can be studied in detail. The results obtained are evaluated seperataly on the basis of horizontal and vertical cutting and also for different types of rock, hs a result, it is found that cutting machines should be operated for cutting angles over 15 degrees.