Background: Osteoarthritis is one of the most frequent chronic diseases that can lead to loss of quality of life. Tai chi is a popular form of exercise among older adults, it encompasses balance, aerobics, flexibility, and weight-bearing exercise with meditation and deep breathing. This study aimed to evaluate the effect of Tai Chi exercises program on the quality of life for osteoarthritis patients. Design: A quasi-experimental research design with one group pre-post was used to conduct the study. Setting: The study was conducted at Outpatient orthopedic Clinic in Benha University Hospital, Egypt. Sample: A purposive sample of 86 osteoarthritis patients was included. Tools: Three tools were used; 1) A structured interviewing questionnaire to collect data about the patients' demographic characteristic, medical history, and patients' knowledge related to osteoarthritis, 2) Mastery Scale was used to assess psychological coping level (Mastery level); 3) Quality of life assessment tool the 36-item Short-Form Health Survey was used. Results: Revealed that improving mean and standard deviation of studied patients' knowledge post program compared by preprogram. There were highly statistical significant differences regarding all knowledge items between pre and post program implementation (P