This study will look at differences in bioanalytical measures among different groups of MS patients and Healthy Volunteers, when administered interferon beta-1a.

Inclusion Criteria:

Healthy Control Subjects (Group 1)

• Must be in general good health.
• Must not have received interferons in the past.

All MS Subjects

• Clinical or laboratory-supported diagnosis of relapsing remitting MS (McDonald et al, criteria numbers 1-4).
• Either on AVONEX® or treatment-naïve.
• Have an EDSS score between 0.0 and 5.5, inclusive.

Exclusion Criteria:

• History of severe allergic or anaphylactic reaction or hypersensitivity to human albumin, to any interferon, to other components of the drug formulation.
• History of intolerance to acetaminophen, ibuprofen, naproxen, and aspirin that would preclude the use of at least one of these during the study.
• History of any clinically significant (as determined by the investigator) cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal, and/or other major disease.
• History of malignancy.
• The presence of any significant medical condition or psychiatric illness not due to MS that, in the investigator's opinion, would interfere with therapy
• History of uncontrolled seizures within the 3 months prior to enrollment.
• History of suicidal ideation or an episode of severe depression within the 3 months prior to enrollment.
• Serious local infection (e.g., cellulitis, abscess) or systemic infection (e.g., pneumonia, septicemia) within 8 weeks prior to enrollment.
• Positive for human immunodeficiency virus (HIV), hepatitis C antibody (HCV) or positive for hepatitis B surface antigen (HbsAg) at screening.

Other inclusion and exclusion criteria apply as per protocol