Abstract Background: Evaluating knee range of motion (ROM) is essential to consider as having broad use in the orthopedic and rehabilitative specialties. Kinovea is a free software that uses a virtual goniometer to measure joints ROM. However, Kinovea reliability in measuring knee full ROM has not been investi-gated. Aim of Study: This study was conductedto investigate the intrarater and interrater reliability of the Kinovea program in measuring knee joint ROM. Subjects and Methods: One hundred healthy male sub-jects from Alexandria University students and employees, with age mean 22.62±3.72 years old and body mass index mean 22.56±1.78kg/m2. Digital camera and laptop with installed Ki-novea software were used. The video recordings of knee ROM for each participant were measured by three raters (1, 2, and 3) using Kinovea computer program in two sessions separated by one week; in order to detect intrarater and interrater reliability. Results: Kinovea program showed excellent intrarater re-liability in measurement of knee ROM; ICC for rater 1 was 0.990, with 95% CI (0.985-0.993), for rater 2, ICC was 0.989 with 95% CI (0.984-0.993), and for rater 3, ICC was 0.972 with 95% CI (0.959-0.981). Kinovea program showed excellent in-terrater reliability in measurement of knee ROM; ICC for trial 1 was 0.987, with 95% CI (0.982-0.991), for trial 2, ICC was 0.989 with 95% CI (0.985-0.993). Conclusion: Kinovea program is a reliable cheap easy ap-plicable tool that can be used in knee joint ROM measurement in everyday clinical practice.