Cardiac troponin I is a sensitive and specific biochemical marker for the diagnosis of acute myocardial injury. We describe a patient with seropositive rheumatoid arthritis (RA) in whom troponin I, measured with a microparticle enzyme immunoassay, was elevated falsely in the absence of acute myocardial infarction. Apparent elevation of troponin I concentration should be evaluated with care in patients with seropositive RA.