Background: Modified radical mastectomy (MRM) is a common surgical procedure used for breast cancer management. MRM often has a negative impact on shoulder function So, early rehabilitation play a critical role in managing shoulder dysfunction. Aim of the study: Determine the effect of early rehabilitation on pain and disability of the shoulder after modified radical mastectomy. Patients and method: A quasi-experimental research design was utilized in this study. It was conducted in the general surgery wards, oncology and general surgery out patient clinics at