The authors examined the right and left ventricle functions in patients with mixed connective tissue disease (MCTD) by Doppler echocardiography. Of 51 patients, 20 had temporary pulmonary arterial hypertension in their case history. According to our knowledge, this is the first study examining the use of Doppler echocardiography and tissue Doppler technique in MCTD patients. Of 51 MCTD patients, 20 had pulmonary arterial hypertension (PAH) in the past 2 years. Diameters of the right and left ventricle, systolic and diastolic blood pressure were measured both in the 51 MCTD patients and in the 30 control subjects (mean age 54.8+/-6.2 years in the case of patients and 54.2+/-8.8 years in the case of control subjects). To estimate the global ventricle functions, the myocardial performance index--as described by Tei et al. (J Am Soc Echocardiogr 6:838-874, 1996)--was applied, which reflects the ratio of the sum of the isovolumetric contraction and relaxation time as compared to the ejection time. The 20 MCTD patients with PAH received cyclophosphamide therapy for 1 year beside the pulse corticosteroid (CS) therapy. In the case of MCTD patients without PAH, different treatments were used: 12 out of 31 patients were treated with sulfasalazine, 5 of whom received a combination of CS and methotrexate, and 14 took nonsteroid antiinflammatory drugs. In the case of the 51 MCTD patients (20 with PAH and 31 without PAH), diastolic function disorder of the left ventricle was detected; the diastolic Ee/Aa velocity quotient of the lateral mitral anulus was lower (p<0.01), and the mean deceleration time was longer (p<0.001) than that of the control group. The Tei index demonstrated the damage of the global ventricle function. The Tei index of the right ventricle indicated global failure of the right ventricle function in the case of MCTD patients complicated with PAH (Tei index 0.36+/-0.07 in MCTD with PAH and 0.28+/-0.04 in MCTD without PAH, p<0.001). The right ventricle function of MCTD patients without PAH was no different from that of the control group. In the case of patients with MCTD, signs of the disorder of the left ventricle diastolic function were observed. Our results suggest that the global impairment of the left ventricle function is the consequence of the disease itself and not the side effect of the treatment. In the case of MCTD patients complicated with PAH, the signs of the right ventricle function impairment proved to be permanent.