The objective is to prove the equivalence in efficacy and safety of HD203 and Enbrel® in combination with Methotrexate in patients with rheumatoid arthritis.

Primary Objective:

To prove the equivalence between two groups by comparing the ACR20 of W24 with the baseline after injecting HD203 25mg and (Enbrel®) 25mg into the patients with rheumatoid arthritis for 24 weeks.

Secondary Objective:

To compare the efficacy of ACR20, ACR50 and ACR70, etc along with safety in adverse event, vital signs, Laboratory test, physical examination and immunogenicity, etc between two groups with baseline after injecting HD203 25mg and (Enbrel®) 25mg into patients with rheumatoid arthritis for 48 weeks.

Inclusion Criteria:

• Males and females who are 20 or over
• Patients who satisfy the classification criteria of Rheumatoid Arthritis according to American Colleague of Rheumatology (ACR 1987)
• Patients who are applicable to functional status I - III of American Colleague of Rheumatology

Exclusion Criteria:

• Patients who have autoimmune diseases other than rheumatoid arthritis or have significant secondary systematic disease caused by rheumatoid arthritis
• Patients who are currently participating in other clinical studies or receiving treatment for drugs not sold in the market or for experiment
• Patients who have significant other diseases that may affect the clinical trial when judged by the clinical trial Investigator
• In the opinion of the investigator, may put the patient at risk because of participation on the study or may influence the patients' ability to participate in the study