Systolic and diastolic functions of both ventricles play a crucial role in the progression of chronic heart failure (CHF). As data about the role of dietary habits in ventricular dysfunction are lacking, we aimed to evaluate the relationship between biventricular diastolic and systolic function and dietary habits in patients with CHF. During 2007, 372 consecutive CHF patients were enrolled. Biventricular systolic and diastolic function was evaluated through echocardiography. Dietary habits were recorded using a food frequency questionnaire, and adherence to a Mediterranean diet was evaluated using the MedDietScore. The MedDietScore was positively correlated with log Smv, left atrial EF and V (p), and inversely correlated with log EA and log Emv/Amv levels (p < 0.05). After adjusting for potential confounders, only log E/A levels were inversely associated with the MedDietScore (p < 0.05). Following analysis per specific aliments, the log E/A ratio was inversely associated with fish intake and olive oil use; the log Emv/Amv ratio was inversely associated with fish intake; log Stv was positively associated with fish, olive oil and pasta intake; log LAKE was positively associated with olive oil use and alcohol drinking (all p < 0.05). This study demonstrated, in a cross-sectional design, a potential beneficial effect of a Mediterranean diet on biventricular systolic and diastolic function.