This extension study will evaluate the effectiveness and safety of ocrelizumab in multiple sclerosis (MS) participants who were previously enrolled in a F. Hoffmann-La Roche (Roche) sponsored ocrelizumab phase IIIb/IV trial (i.e. the Parent, P-trial).

This is a single arm, open label, multicenter extension study in participants who completed treatment period with ocrelizumab in the Roche P-trials. Participants will receive treatment with ocrelizumab as single 600 mg infusions every 24 weeks for two years.

Inclusion Criteria:

• Signed Informed Consent Form
• Able to comply with the study protocol, in the investigator's judgment
• Completed the treatment period of Roche sponsored ocrelizumab P-trials

Exclusion Criteria:

• Hypersensitivity to ocrelizumab or to any of its excipients.
• Participantss in a severely immunocompromised state until the condition resolves.
• Evidence of any adverse event potentially attributable to ocrelizumab, for which the local label recommends permanent discontinuation.
• Existence of a contra-indication as per SmPC
• Prohibited concomitant medication as specified in protocol
• Participants intending to become pregnant during the study or within 6 months after the last dose of the study drug in the parent study

For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data\_sharing