Background: Multiple sclerosis is the most common permanent neurological disorder affecting young adult causing strength deficits. Aim of the study: This study was conducted to investigate influence of selected aerobic exercises on serum Vitamin D level in patients with multiple sclerosis. Subject and methods: 30 patients (20 female and 10 male) with relapsing remitting multiple sclerosis recently diagnosed by Expanded Disability Status Scale score less than 5, vitamin D insufficiency less than 20- 30 ng/mL, age from 20 to 40 years old with body mass index less than 25 kg/m² were recruited, assessed for and assigned into 2 groups. They received treatment program as follows: control group (A) received conventional medical treatment (Corticosteroids, Interferon beta medications, Dimethyl fumarate, muscle relaxants, medications to reduce fatigue)in addition to vitamin D supplementation only, while experimental group (B) received conventional medical treatment(Corticosteroids, Interferon beta medications, Dimethyl fumarate, muscle relaxants, medications to reduce fatigue), vitamin D supplementation in addition to selected aerobic exercises. the outcome measures included serum vitamin D level by lab test ,timed 25 walk test by measure timing of performance of lower limb gait in multiple sclerosis. Results: both groups showed significant difference in the outcome measures in the post treatment assessment, but the selected aerobic exercises (B) showed a more significant improvement over the control group at p-value >0. 001. Conclusion: selected aerobic exercises is an effective physical therapy modality when added to the conventional medical treatment (Corticosteroids, Interferon beta medications, Dimethyl fumarate, muscle relaxants, medications to reduce fatigue) so it may provide better outcomes for a patient with multiple sclerosis.