Abstract Background: The prevalence of breast cancer has risen dra-matically in recent years and became the second most common cause of cancer mortality in women, after lung cancer. Mastec-tomy is the most common surgery for treating breast cancer and have the highest survival rate. Aim of Study: The study's goal is to demonstrate how alter-ations in gait characteristics are caused by mastectomy. Subjects and Method: One hundred & forty females were divided into two groups. Seventy females post-mastectomy serves as a study group and another seventy healthy group. The study group's age ranged from 30 to 67 years and sub-divided into 2 other groups. (group A) young group from 30 to 44 years and (group B) old group from 45 to 67 years. All candidates were required to move back and forth in the physical therapy room at their own pace while dressed comfort-ably and with passive markers on their feet. Their walk was recorded by HD Nikon camera for one whole minute. Following that, the information was gathered and processed by HD-Cam Kinovea Software to derive gait parameters. The parameters collected were Step Length, Stride Length, Step Time, Cadence, and Left-Right Asymmetry. Results: The results of current study revealed significant differences in all parameters between Controlled and Study groups (p<0.01), considering the age groups within the study group, there were differences between young and older groupin all parameters, so the age is considered to be one of the reason of the deterioration of the gait parameters. Conclusion: There are gait parameters changes as a result of mastectomy as a surgery.