This study is designed to assess whether co-administration of CP-690,550 and oral contraceptives will effect the metabolism of the oral contraceptives in healthy volunteers.

Inclusion Criteria:

• Healthy female subjects
• No evidence of active or latent or inadequately treated infection with Mycobacterium tuberculosis

Exclusion Criteria:

• Any medical reason which would contraindicate the administration of oral contraceptives
• Clinically significant infections within the past 3 months or history of febrile illness within 5 days
• Positive screening test for Hepatitis B surface antigen, anti Hepatitis C antibody, or human immunodeficiency virus
• Pregnant or nursing women, and women of childbearing potential who are unwilling or unable to use an acceptable method of nonhormonal contraception