The ubiquity of plastics in the environment poses a significant risk for both human health and natural ecosystems. Especially the fiber type plastics have a quite high share among these plastics. The textile industry is one of the most important sources of fibers. Recycling is one of the solutions offered to reduce the environmental impact of textile materials. In this study, the release of fibers from the knitted fabrics produced from recycled (R-PET) and virgin polyester (PES) yarns was investigated. Knitted fabrics were washed three times under the same washing conditions according to the TS EN ISO 105-C06 standard by James H. Heal Gyrowash washing machine. It was determined that R-PET knitted fabrics released almost 2.3 times more fibers (4489.93 fiber L⁻¹; 368094.07 fiber kg⁻¹) than the virgin PES fabrics (2034.26 fiber L⁻¹; 167436.58 fiber kg⁻¹). The amount of the released fibers showed a significant reduction with an increase in the number of washing cycles for both R-PET and virgin PES samples. This study showed that the knitted fabrics produced from R-PET released more fiber having the shorter length as compared to virgin PES.