Background: Mastectomy after breast cancer is usually accompanied by shoulder dysfunction which interferes with the daily life activities of the patients and causes physical and psychological impairments. Objectives: This study aimed to assess the impact of scapular mobilization and strengthening exercises on shoulder function post mastectomy. Patients and methods: A single blinded randomized controlled trial included forty female patients, their ages ranged from 40 to 55 years suffering from post-mastectomy shoulder dysfunction. They were allocated randomly into two equal groups: the study group (group A), managed by scapular mobilization and strengthening exercises besides their conventional physical therapy program and the control group (group B), managed by the conventional physical therapy program only. Trial was applied for (three sessions/week) and lasted for four weeks. Shoulder pain and impairment, upward rotation of the scapula and shoulder range of motion were measured pre- and post- four-weeks of intervention. Results: after 4 weeks of treatment, percentage of change in shoulder pain and disability index (SPADI), upward rotation of scapula, shoulder flexion, abduction and external rotation was 34, 103.55, 45.71, 63.19 and 31.41% respectively in the study group and14.77, 58.42, 22.25, 30.30 and 23.40% in the control group, respectively. In all measures, there was a statistically significant difference in favour of the study group (p < 0.001). Conclusion: It could be concluded thataddingscapular mobilization and strengthening exercises are more effective in improving shoulder function regarding pain and ROM post-mastectomy than using the conventional physical therapy program only.