Connective tissue disease (CTD) encompasses several disease or abnormal states characterized by inflammatory or degenerative changes in connective tissue. These disorders affect many organs, including the heart. However, the long-term survival of patients with cardiomyopathy and CTD is not known. The prognostic implications of different categories of CTD were studied in patients with cardiomyopathy. One thousand seven hundred patients with initially unexplained cardiomyopathy who underwent endomyocardial biopsy from 1983 to 2003 at The Johns Hopkins Hospital were evaluated. Seventy-one subjects were diagnosed with CTD. This cohort was followed for an average of 5.1 years. Among the different disorder categories within CTD, there was a significantly lower survival rate for subjects with undifferentiated CTD (adjusted hazard ratio for death 2.39, 95% confidence interval 1.27 to 4.48, p = 0.007) and a trend toward decreased survival in patients with systemic sclerosis (adjusted hazard ratio for death 1.75, 95% confidence interval 0.93 to 3.29, p = 0.081) compared with those with idiopathic dilated cardiomyopathy (DCM). No significant survival difference was observed between systemic lupus erythematosus and idiopathic DCM (p = 0.41). The long-term outcomes of subjects with CTD and myocarditis were not statistically different from the outcomes of those with CTD and no myocarditis (p = 0.71). In conclusion, the diagnosis of cardiomyopathy and either undifferentiated CTD or systemic sclerosis appears to be a poor prognostic indicator compared with the diagnosis of idiopathic DCM. Patients with systemic lupus erythematosus and cardiomyopathy have a similar prognosis to those with idiopathic DCM. Finally, the presence of myocarditis does not alter the survival of patients with CTD and cardiomyopathy.