The attempt to reuse plastic waste in concrete is a significant issue because it helps in preserving natural resources and in decreasing environmental contamination. The main aim of this research is to investigate the impact of adding Polyethylene terephthalate (PET) particles on the characteristics of concrete. PET particles were utilized as a partial replacement of fine aggregate by 2.5%, 5%, 7.5%, and 10% of volume. Mechanical characteristics of concrete were evaluated by various tests such as compressive strength, flexural strength, and splitting tensile strength. Absorption rate test, dry unit weight test, and ultrasonic pulse velocity test were conducted to assess the performance of concrete. Fresh concrete properties were determined using a slump test. Different water-to-cement ratios of 0.4 and 0.55 and cement content of 400 kg/m3 and 300 kg/m3, respectively, were used to prepare samples. The compressive strength test was conducted on cubic concrete samples with dimensions of 15×15×15 cm. Beams with dimensions of 10×10×50 cm were utilized to measure the flexural strength of all mixtures. The findings were determined at 28 days of curing. It revealed that PET mixtures had lower workability compared to reference mixture. The mixture with 5% PET achieved maximum compressive strength increase by 7.1%, and 12.39% with respect to that of the reference mixture at w/c=0.4, and 0.55, respectively. Flexural strength takes the same direction as compressive strength. Indirect tensile strength decreased by increasing the ratio of PET. The elastic modulus of PET mixtures decreased with an increase in PET content.