Background: Upper limb dysfunction following mastectomy is a prevalent problem that frequently occurs after breast cancer surgery. Approximately 67% of breast cancer patients encounter difficulties with their arm or shoulder, such as reduced strength, decreased ROM, along with functional limitations, after undergoing surgery. Purpose: the study was carried to compare Pilates exercise versus virtual reality in improving upper limb dysfunction after mastectomy. Methods: Sixty patients with upper limb dysfunction post Mastectomy got involved in this study. Their ages ranging between 35 and 55 years. they were randomly distributed into two equal groups. The methods of assessment included electronic hand dynamometer to assess hand grip strength, smartphone inclinometer to assess shoulder range of motion and Arabic version of The American Shoulder and Elbow Surgeons Evaluation Form to assess upper limb function. Group (A) received Pilates exercise plusconventional physical therapy program (Mobilization exercises and ROM exercises)as well asroutine medical treatment. Group (B) received virtual reality plus conventional physical therapy program (Mobilization exercises and ROM exercises)as well as routine medical treatment. Results: There was a significant improvementin shoulder flexion ROM, ASES as well as hand grip followingtreatment in both groups compared with that prior to treatment (p > 0.001). The percent of change in shoulder flexion, abduction and external rotation, ASES and hand grip of group A was 42.49, 35.49, 56.87, 76.09 and 14.45% respectively and that in group B was 21.83, 26.52, 35.62, 38.85 and 8.49% respectively So The results showed that there was decrease in upper limb dysfunction in group A compared to group B ,in relation to shoulder ROM, upper limb function and hand grip , There was a significant improvement in the flexion , abduction and external rotation ROM of shoulder , ASES, hand grip of group A compared with group B following treatment Conclusion: it was concluded that Pilates exercise is superior to virtual reality in improving upper limb dysfunction