This study will compare injection site pain levels between current Humira® formulation versus a new formulation of Humira in patients with Rheumatoid Arthritis (RA), who are either currently on a stable dose (minimum six consecutive doses) of on-label Humira or biological naïve who will be prescribed on-label Humira as treatment for their Rheumatoid Arthritis. The study is being conducted in two countries, Belgium (3 sites) and the Czech Republic (3 sites).