Background : Recognition of ischemic right ventricular(RV) dysfunction in the course of inferior wall left ventricular(LV) acute myocardial infarction is important in clinical practice., because it is associated with a higher in-hospital morbidity and mortality. The Doppler total ejection isovolume(Tei) index is useful for estimating global cardiac function. However, the clinical usefulness of RV Tei index to diagnose subclinical RV dysfunction has not been investigated. The purpose of this study was to assess the clinical value of RV Tei index for diagnosis of subclinical RV ischemia associated with inferior wall acute myocardial infarction who did not have definite ECG changes at right precordial leads. Methods : The study population consisted of 22 consecutive patients with acute inferior myocardial infarction who did not have specific ST segment changes at right precordial leads. RV Tei index was measured by two dimensional echocardiography and RV ejection fraction(EF) was measured by multigated blood pool(MUGA) scan. We defined subclinical RV dysfuntion as estimated RVEF was £ 40% by MUGA scan. Results : In all patients, two dimensional echocardiography showed no significant evidence of RV regional wall motion abnormality. In patients with decreased RVEF(n =10) by RV MUGA scan significantly increased RV Tei index compared with those with normal RVEF(>40%) group(n=12) (0.61짹0.12 vs 0.35짹0.14, P = 0.01). In patients with decreased RVEF group right atrial(RA) pressure by cardiac catheterization significantly increased compare with normal RVEF group(7짹2mmHg vs 10짹3mmHg, p<0.05). Conclusion : RV Tei index is simple and useful non-invasive method for diagnosis of subclinical RV dysfunction associated with inferior wall acute myocardial infarction who did not have typical ECG changes at right precordial leads.