Objective: The aim of the present study was to evaluate cardiac involvement in patients with active rheumatoid arthritis (RA). Methods: Forty patients with active RA participated. All were submitted to standard Doppler echocardiography and myocardial performance index (MPI) grading. Results: There were left and right ventricular diastolic function abnormalities in RA patients. Left ventricular MPI was also significantly higher than in controls (P < 0.05). A relationship was found between left ventricular early diastolic (E)/atrial (A) flow velocities (E/A ratio), isovolumic relaxation time (IRT), and disease duration (r = -0.47 and P = 0.002, r = 0.618 and P = 0.000, respectively). Conclusion: Diastolic function was impaired in both ventricles in patients with active RA. There was a direct relationship between some of the parameters of left ventricular diastolic function and disease duration as well. These findings suggest a subclinical myocardial involvement in RA patients. © Springer-Verlag 2003.