Submitted in fulfillment of the Degree of Masters in Technology: Clinical Technology, Durban University of Technology, 2011. / Background: Idiopathic dilated cardiomyopathy (IDC) is a primary myocardial disease of unknown cause characterized by left ventricular or biventricular dilatation and impaired myocardial contractility. Idiopathic dilated cardiomyopathy (IDC) is the second commonest cause of heart failure in Africa. Some patients with idiopathic dilated cardiomyopathy present with significant pulmonary hypertension (PHT) which maybe out of keeping with the usual degree of PHT seen in patients with this disorder. Methods and Material: This is a prospective and longitudinal follow-up study of 66 patients with IDC who were evaluated after satisfying the inclusion and exclusion criteria of this study. The clinical evaluation of each patient included a complete medical history, physical examination, 12 lead electrocardiogram, 2D-echocardiography, continuous wave (CW), pulsed wave (PW), and tissue Doppler imaging (TDI). Results: The mean age of all patients was 48.5 ± 12.8, with 39/66 (59.1%) patients being male. The prevalence of pulmonary arterial hypertension (PAH) was documented in 47 patients (71.2%, 95% CI: 59 - 83%). Mean left ventricular ejection fraction (LVEF) was 25.3 ± 8.8%, and mean left atrial volume index (LA volume) was 44.5±19.8 ml/m2. Mitral regurgitation (MR) occurred in 56/66 (84.8%) of patients with moderate or severe MR detected in 60.6% of all cases of IDC. The presence of a tricuspid regurgitant jet was found in 56/66 (84.9%), with (95% CI: 75 -93%). Right ventricular dilatation was found in 65/66 (98.5%), with (95% CI: 95 - 101%). ii Age, LA volume, LVEF and MR were included into a multivariate logistic regression model to predict PAH. Only MR presence was independently associated with PAH adjusted (OR 6.02, 95% CI: 1.15- 31.47) (p= 0.03). Conclusion: The study has shown that there is a significant prevalence of pulmonary arterial hypertension (PAH), right heart involvement and tricuspid regurgitant jet in IDC patients. The present study also showed that in patients with dilated cardiomyopathy, the degree of mitral regurgitation was a good predictor of PAH.