<b><i>Background:</i></b> Repeated inter-dialysis water retention contributes to the development of left ventricular hypertrophy and failure, which is responsible for significant mortality of end-stage renal disease (ESRD) patients. The left atrium has a thin wall, which makes it even more prone to preload changes. In the general population with heart failure with preserved ejection fraction (HFpEF), left atrial function is even worse than that in patients with reduced ejection fraction. We hypothesized that repeated water retention is related to left atrial dysfunction in ESRD patients treated by hemodialysis and that the expected changes would be related to the brain natriuretic peptide (BNP) levels. <b><i>Methods:</i></b> Forty six patients were enrolled. Left atrial end-diastolic and end-systolic volumes and left atrial ejection fraction (LAEF) were recorded by echocardiography just before and just after dialysis and then analyzed offline. Moreover, BNP was analyzed also prior to dialysis and after. Effects of dialysis were tested using paired t test and the correlation analysis was applied to test associations. <b><i>Results:</i></b> LAEF was inversely related to the dialysis vintage (r = -0.62, p = 0.001) and patient's age (r = -0.48, p = 0.005) and it did not increase after dialysis despite the decrease of left atrial volume. BNP was related to left atrial volume index (r = 0.45, p = 0.019) and to LAEF (r = -0.57, p = 0.003). <b><i>Conclusions:</i></b> LAEF is decreased especially in long-term dialyzed patients and does not improve after dialysis despite the decrease of left atrial volume. Inadequate contractility reserve of the left atrium is similar to the non-ESRD patients with HFpEF and might help explain the high prevalence of heart failure in ESRD patients.