Cardiac vagal reflexes were investigated in 19 dialysis patients, with the aim of verifying whether parathyroid hormone, proposed as an important uremic neurotoxin, plays a role in the development of uremic vagal neuropathy. The results indicate that parasympathetic control of heart function is frequently impaired in uremics. Plasma parathyroid hormone levels were significantly correlated with the time on dialysis. However, a correlation between autonomic disturbances and plasma parathyroid hormone concentrations was not found in this study.