We studied the relation of left atrial mechanical function to the hormonal response in 14 patients with idiopathic dilated cardiomyopathy. Left atrial volumes were echocardiographically measured at mid-diastole and end-diastole. The results showed that left atrial volume was significantly correlated with the hormonal response, indicating a potential link between left atrial function and hormonal regulation in patients with dilated cardiomyopathy. This study highlights the importance of left atrial function in the context of heart failure and suggests that left atrial volume may be a useful marker for predicting patient outcomes.