The application of the traditional homogenization process used in yogurt production under higher pressure, such as 50-200 MPa, is a new approach to improving yogurt structure and quality effectively. High-pressure homogenization (HPH) is considered a technology that changes the microstructure, water holding capacity, viscosity, and sensorial properties of yogurts by affecting fat globules and protein structures depending on fat content. In this study, the effects on bacterial growth, acidification kinetics and viscosity development were investigated in the production of yogurt from fatty and semi-skimmed milk with HPH. HPH treatment and fat content had a positive effect on the bacterial growth rate, and the maximum counts of L. bulgaricus and S. thermophilus were determined in the yogurt sample made from fatty milk treated with 100 MPa pressure as 8.65 and 9.16 log cfu/g, respectively.Also, the pH and viscosity change during incubation was affected and the Vmax and μmax values for fatty milk treated with 100 MPa pressure reached maximum values of 1.67x10 -2 pH unit/min and 2.35x10 -2 Pa.s units/min, respectively. With the HPH treatment, the fermentation time in fatty yogurt was shortened by 60 min compared to the control sample.