Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects approximately 1% of the worldwide population. It primarily targets the synovial membrane of joints, leading to a synovial proliferation, joint cartilage lesion and erosions in the adjacent bone tissue. The disease is usually progressive and if the inflammatory process is not adequately suppressed, joint deformity takes place, leading to a significant functional disability and work incapacity. Over the last decade, biological therapy was established as a major step towards disease control in those patients who experienced failure after treatment with disease-modifying antirheumatic drugs. Despite the growing number of biological agents with different immunological targets, a significant number of patients do not receive appropriate disease control, or have the use of these agents limited because of adverse events. As such, the search for new molecules with a higher efficacy and better safety profile is ongoing. This article focuses on a new drug, tofacitinib, which is a synthetic disease-modifying antirheumatic drug for treatment of RA. Preclinical studies in arthritis and transplantation animal models are reviewed as a background for the possible use of tofacitinib treatment in humans. Four Phase II (one A and three B dose-ranging) trials lasting from 6 to 24 weeks in RA patients showed significant American College of Rheumatology 20 improvements as early as week 2 and sustained at week 24 in two studies. Tofacitinib Phase III studies in RA are included in a clinical program called 'ORAL Trials'. Long-term follow-up from ongoing studies will contribute to a more accurate tofacitinib efficacy and safety profile. Trials in other illness such as psoriasis, psoriatic arthritis, renal transplant rejection prevention, inflammatory bowel diseases and dry eye are underway.