Aims: The prognostic stratification of patients with Idiopathic Dilated Cardiomyopathy (iDCM) is a difficult task. Here, we assessed the additive value of the evaluation of biomarkers of inflammasome activation and systemic inflammation for the long-term risk stratification of iDCM patients. Methods and Results: We studied 156 ambulatory iDCM patients (mean age 58 years, 77% men, 79% in NYHA class 1-2, median Left Ventricular Ejection Fraction (LVEF) 35%, mean sodium 139 mEq/L, median BNP 189 pg/mL, median IL-1 beta (IL-1 beta) 1.08 pg/mL, median IL-6 1.7 pg/mL and median IL-10 2.7 pg/mL). During the follow-up period of 89.6 months, 35 patients (22%) died/underwent heart transplantation. Patients who died/underwent heart transplantation were more likely to be male, to be in NYHA class III, to have atrial fibrillation, to have lower LVEF and higher BNP levels. IL-1 beta, IL-6 and IL-10 levels did not differ significantly between the groups of patients with good or bad prognosis. IL-1 beta levels did not vary significantly among either the different NYHA classes or the quartiles of LVEF. In a multivariable model, however, IL-1 beta was a strong and independent predictor of all-cause mortality (HR 1.193, 95% CI 1.056 -1.349, p=0.005 for log squared transformed values). Other factors associated with the outcome were: male gender, presence of atrial fibrillation and sodium concentration. The estimated time-dependent ROC curve of the multivariable model showed an AUC 0.74 (95% CI 0.65-0.86). Conclusions: Serum levels of IL-1 beta could be useful to predict the long-term outcome of patients with iDCM.