In idiopathic dilated cardiomyopathy (DCM), myocardial deformational parameters and their relationships remain incompletely characterized. We measured those parameters in patients with DCM, during left ventricular reverse remodeling (LVRR). Prospective study of 50 DCM patients (in sinus rhythm), with left ventricular ejection fraction (EF) <40%. LVRR was defined as an increase of ten units of EF and decrease of diastolic left ventricular diameter (LVDD) in the absence of resynchronization therapy. Performed morphological analysis, myocardial performance quantification (LV and RV Tei indexes) and LV averaged peak systolic longitudinal strain (SSR long) and circumferential strain (SSR circ). At baseline, mean EF was 25.4 ± 9.8%, LVDD was 62.4 ± 7.4 mm, LVDD/BSA of 34.2 ± 4.5 mm/m2 and 34% had MR grade >II/IV. LVRR occurred in 34% of patients within 17.6 ± 15.6 months and was associated with a reduced rate of death or heart failure hospitalization (5.9% vs. 33.3; p = 0.03). Patients with LVRR had a final EF of 48.9 ± 7.9% (Δ LV EF of 22.4%) and there was a significant decrease (p < 0.05) in: LVDD/BSA, LV systolic diameter/BSA, LV diastolic volume, LV systolic volume, LV mass; an increase (p < 0.05) in sphericity index. However, measures of diastolic function (LA volume/BSA, e'velocity and' E/e'ratio), final LV and RV Tei indexes were not significantly different from baseline. Additionally, final SSR circ and SSR long values were not different from basal. Patients who recovered EF >50% (n = 10), SSR circ and SSR long were inferior to normal. Improvement in EF occurred in one-third of DCM pts and was associated with a decrease of major cardiac events. There was an improvement of diastolic and systolic volumes and in sphericity index, confirming truly LV reverse reshaping. However, myocardial performance indexes, SSR long and SSR circ in reverse-remodeled DCM were still abnormal, suggesting a maintained myocardial systolic and diastolic dysfunction.