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Background. It is not known whether there are differences in clinical characteristics and outcomes of patients with familial and idiopathic dilated cardiomyopathy (DCM) in an African setting. Purpose. To compare the clinical characteristics and outcomes of familial and idiopathic DCM. Methods. We performed a retrospective study of familial and idiopathic DCM at Groote Schuur Hospital, Cape Town, between 1 February 1996 and 31 December 2009. Clinical, electrocardiographic (ECG) and imaging characteristics were compared, in addition to treatment and survival. Results. Eighty patients with idiopathic DCM and 40 familial cases were studied. ECG T-wave inversion was significantly more frequent in familial DCM (87.5%) than in idiopathic cases (68.8%) (p=0.014), whereas idiopathic patients had a higher prevalence of pathological Q waves (32.5%) than familial cases (12.5%) (p=0.028). Cardiac chambers were significantly more dilated with poorer systolic function in idiopathic than familial cases. A mortality rate of 40% after a median follow-up of 5 years was, however, similar in both groups. The presence of New York Heart Association functional class III and IV symptoms was an independent predictor of mortality (odds ratio (OR) 3.85, 95% confidence interval (CI) 1.30 - 48.47, p<0.001), while heart transplantation was an independent predictor of survival (OR 4.72, 95% CI 1.31 - 72.60, p=0.026) in both groups. Digoxin use without serum monitoring was a significant predictor of mortality in idiopathic DCM (OR 1.62, 95% CI 1.04 - 3.98, p=0.037). Conclusion. Patients with idiopathic DCM have greater cardiac dysfunction than those with familial disease, but mortality is similarly high in both groups. Digoxin use without drug level monitoring may be associated with increased mortality in idiopathic DCM.