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<0.001). There was improvement in quality of life for osteoarthritis patients post program Tai Chi exercises with highly statistical significance. About 65.1 % of the studied osteoarthritis patients had low total mastery upon osteoarthritis which decreased to 7% post program implementation. While high total mastery upon osteoarthritis was found on 3.5% of the studied patients that increased post program to 43.0%. Conclusion: Implementation of a Tai Chi exercise program showed positive impact and effective improvement in knowledge, mastery, and quality of life, raising awareness, and improving outcomes among patients with osteoarthritis. Recommendation: Adequate scientific brochure or booklets should be provided for patients with osteoarthritis in orthopedic clinics, with explanation of Tai Chi exercise.