Clinical and laboratory findings were compared in 65 women and 238 men with invasively documented idiopathic dilated cardiomyopathy. Women had more severe symptoms (New York Heart Association class ≥III in 48 vs 39%; p < 0.05), presented more frequently with heart failure signs (63 vs 41%; p < 0.01), and had a higher cardiothoracic ratio (0.56 ± 0.06 vs 0.53 ± 0.06; p < 0.05) and higher frequency of left bundle branch block (41 vs 29%; p < 0.05). Echocardiographic measurements in women showed significantly greater left ventricular (LV) end-diastolic (42 ± 7 vs 39 ± 6 mm/m²; p < 0.0001) and end-systolic (36 ± 7 vs 33 ± 6 mm/m²; p < 0.001) diameters, and mean myocardial thickness (11 ± 2 vs 10 ± 2 mm; p < 0.05). Exercise duration was shorter in women than in men (7 ± 3 vs 10 ± 4 minutes; p < 0.001). After 18 ± 16 months, 9 women and 27 men died, and 7 and 17, respectively, received transplants. Transplant-free survival was not significantly different according to gender. By Cox multivariate analysis, LV ejection fraction was a significant independent predictor of cardiac death or heart transplantation in both sexes (p < 0.05 in men, and p < 0.005 in women), together with left atrial diameter index (p < 0.01) in women, and mean pulmonary artery pressure (p < 0.001) in men. In conclusion, women with idiopathic dilated cardiomyopathy present a more advanced phase of the disease with greater LV dilation, but do not have a different prognosis.