This is a phase IV, multicenter, randomized, double blind clinical trial. The investigators will study 48 patients with remitting relapsing multiple sclerosis (MS) experiencing moderate or severe attack receiving immunomodulatory therapy or not. Patients will be randomly assigned to one of the two groups.

This is a multicenter, randomized, double blind clinical trial to test whether oral methylprednisolone (MP) is not inferior to intravenous methylprednisolone for the treatment of multiple sclerosis (MS) relapse in terms of clinical and radiological efficacy.

Patients will be randomly assigned to one of the following two groups.

Group A: methylprednisolone 1.000 mg/day intravenous administered during three days + placebo of methylprednisolone orally administered

Group B: methylprednisolone 1.250 mg/day orally administered during three days + placebo of methylprednisolone intravenously administered.

Clinical visits will be conducted at 7, 28 and 90 days after treatment starting.

Inclusion Criteria:

1. To have been diagnosed MS Remittent Recurrent according to Mc Donald 20052 criteria.
2. To have an EDSS between 0 and 5 before the relapse.
3. The symptoms have begun after at least one month of previous stability.
4. The symptoms have started maximum 15 days before the inclusion.
5. The patient is capable of having an adequate communication with the investigator and to carry out with the clinical trial requisites.
6. To be or not to be with allowed immunomodulatory therapy (IFN-B /AG).
7. To be capable and to be willing to ingest the medication.

Exclusion Criteria:

1. First inflammatory neurological episode (relapse).
2. Multiple sclerosis secondary progressive or primary progressive.
3. The symptoms have gone on for less than 24 hours.
4. To be in treatment or have been treated with corticoids during the three months before.
5. Patients in treatment with immunosuppressors (azathioprine, mitoxantrone, ciclofosfamide...)
6. Pregnancy or breastfeeding or women in fertile age who don't use contraceptives measurements.
7. Illnesses with contraindication treatment with corticoids.
8. Antecedents of serious adverse effects or hypersensitive to related study medication.
9. Patients who wouldn´t be able to perform periodic RMN explorations, patients who are not collaborative or who need anesthesia.
10. Patients with intolerance to lactose.
11. Patients with allergy to contrast used in RMN.
12. Patients with chronic kidney disease.
13. Patients in treatment with natalizumab.