Background A 75-year-old woman with rheumatoid arthritis presented with a 4-year history of chorea to a hospital movement disorder clinic. The involuntary movements were initially mild, affecting only the right side of the body, but gradually worsened and became bilateral. There was no relevant family history. Medications included hormone replacement therapy (HRT), diclofenac sodium, vitamin D, folic acid, methotrexate and zopiclone. On examination, bilateral choreiform movements were seen, affecting the face and limbs, with the right side more severely affected than the left. Investigations Neuropsychological testing, laboratory blood and DNA testing, echocardiogram, MRI of the brain, and brain perfusion single-photon emission computed tomography (SPECT) scanning.Diagnosis HRT-related chorea, possibly caused by a predisposition secondary to rheumatoid arthritis and small-vessel ischemic disease, or subclinical childhood rheumatic fever. Management Discontinuation of HRT.