BACKGROUND Few reports in the literature describe the association of rheumatoid arthritis and transient thyrotoxicosis. We report a case of rheumatoid arthritis and painless thyroiditis presenting simultaneously and acutely with a cluster of symptoms that initially made the diagnosis of rheumatoid arthritis very challenging. METHODS A 41-year-old Caucasian male presented with complaints of malaise and decreased range of motion in the left elbow. Physical examination and laboratory evaluation established the diagnosis of rheumatoid arthritis and painless thyroiditis. CONCLUSIONS When patients with rheumatoid arthritis present with numerous "extra articular" and constitutional symptoms, evaluation of thyroid disorder with thyroid function test should be considered to help establish the correct diagnosis.