This open-label, randomized, cross-over study evaluated the effect of tocilizumab (TCZ) on the pharmacokinetics and pharmacodynamics of a common oral contraceptive (OC) in female patients with active rheumatoid arthritis (RA) and in healthy female volunteers of child bearing age. The RA patients received OC in combination with TCZ, whereas the healthy volunteers received OC only. The RA patients received OC in 3 cycles of 21 days each; TCZ 8 mg/kg was administered once as an intravenous infusion on the first day of Cycle 2. The healthy volunteers received OC for only one 21-day cycle.