Inclusion Criteria:

1. Written informed consent obtained.
2. Age between 18 and 50 years inclusive.
3. Male and female patients.
4. Clinically definite or laboratory supported definite RR MS (Poser et al, 1983) for not less than 2 year.
5. Two clinically documented relapses during the preceding 24 months.
6. No relapse or relapse related neurological deterioration for at least 30 days prior to entry in the study.
7. Patients EDSS score from 1 to 3.5 (probably to be extended to 5.5).
8. MRI activity. At least one enhancing lesion during the baseline MRI run-in study .
9. Women capable of having children must agree to use adequate con-traceptive methods (condoms with spermicides, IUCD, oral contraceptives or other adequate barrier contraception).
10. Caregivers agreement to assist the patient to comply with study requirements, if neces-sary (e.g. study drug administration, visits to center).

Exclusion Criteria:

1. Any form of Multiple Sclerosis other than relapsing-remitting.
2. Any other disease which could better explain the patient's signs and symptoms.
3. Any other disabling condition, which could interfere with the clinical evaluation.
4. Pregnancy or lactation.
5. Medical psychiatric, or other conditions that compromise patient's ability to give informed consent, to comply with the trial protocol, or to complete the study.
6. Alcohol or drug abuse in the 90 days preceding screening visit.
7. Uncontrolled clinically significant heart diseases, i.e., cardiac arrhythmias, uncon-trolled angina pectoris, uncompensated congestive heart failure
8. Clinically significant liver, renal and bone marrow dysfunction as defined by the ran-ges of laboratory evaluations. The following ranges (see table 1) for key laboratory evaluations will be considered as adequate for inclusion: