Three generations of regenerated cellulose fibers, such as viscose, modal and lyocell fibers are among the most important fibers from the point of textile and environmental aspects due to the natural structures and properties. Different production process and production conditions for conventional viscose, modal and new lyocell fibers cause differences in the structure of the fibers in spite of the same chemical compositions. In this study, the structural properties of viscose, modal and lyocell fibers and yarns were investigated. Besides, the influence of structural characteristics of the fibers on the performance properties of knitted fabrics such as pilling, bursting strength, color efficiency and thermo physiological properties were determined. It was determined that due to the fiber structure, pilling tendency of viscose fabric is higher compared to lyocell and modal grey fabrics. Since the tensile strength of lyocell fiber is higher, fabric bursting strength of lyocell fabric is higher than the modal and viscose fabrics. As the thermal conductivity of lyocell fabric is higher, it gives cool feeling compared to viscose and modal fabrics. The highest colour efficiency is obtained from lyocell fabrics.