In patients with dilated cardiomyopathy (DCM) of different aetiologies, a variable frequency of improvement in the left ventricular (LV) systolic function has been reported, while in patients with a 'classic' idiopathic DCM, the frequency of improvement is still under debate, and clinical and haemodynamic predictors of recovery of the LV function are needed. The aim of the present study was to determine the frequency of improvement in the LV systolic function in idiopathic DCM and to identify predictors of reversibility of the impaired LV contractility. A sample of 98 consecutive patients with idiopathic DCM was retrospectively evaluated. Echocardiographic and Doppler measurements were directly taken from the routine echo-report. LV systolic function was assessed semiquantitatively using a score index (SFSI). According to the improvement in the LV systolic function, the patients were divided into group 1 patients with improvement, and group 2 patients without improvement. During a follow-up of at least 12 months, 19 patients (19%) showed an improvement, with a significant increase in the mean SFSI; all these group 1 patients survived without heart transplant; in group 2, 18 patients (23%) died and 3 (4%) received a heart transplant. Patients in group 1 had a significantly shorter duration of symptoms (P=0.0045), a younger age (P=0.006), a shorter DtE (P=0.04), a lower SFSI (P<0.01), a worse NYHA class (P<0.001) and more frequently had a history of hypertension (P<0.0001). The same variables were significant predictors of improvement at the univariate analysis. At the multivariate logistic regression analysis, a shorter duration of symptoms (P=0.02), a history of hypertension (P=0.003), and a worse NYHA class (P=0.01) were independent predictors of improvement. A relatively large percentage of patients with an idiopathic DCM will have a marked improvement in the LV systolic function. This is more likely to happen in the presence of a short duration of symptoms and a history of hypertension. After an improvement, the prognosis is excellent.