The purpose of this study is to test MK0812 on disease activity in patients with relapsing-remitting MS. Disease modifying activity will be assessed by measurement of brain lesions via MRI brain scans and an open label extension is offered.

Inclusion Criteria:

• Patients must have clinically definite relapsing-remitting MS onset within last 10 years and have had at least 1 objective clinical exacerbation in the last year OR a recent clinically isolated syndrome suggestive of MS occurring 3-12 months before screening
• Patients must be relatively healthy

Exclusion Criteria:

• Patient has primary progressive MS