Background: Previous studies assessing esophageal motility in chronic renal failure (CRF) patients had no consistency in their findings. These studies evaluated esophageal contractility in re- sponse to dry/water swallows. Our aim was to reassess esophageal motility in CRF patients to better define its abnormalities. To un- mask minor defects not seen in conventional dry/water manometry we also evaluated esophageal contractility in response to a highly viscous substance. Methods: Fifteen controls and nine asymptomatic CRF patients underwent esophageal manometry with dry swallows, swallows of 5 mL of water (1 centipoise) and 5 mL of sugar cane syrup (24500 centipoise). CRF patients were compared with controls for esopha- geal motility parameters, considering each type of swallow (dry/ water/syrup). Results: CRF patients had: tendency for higher lower esophageal sphincter (LES) resting pressure (P = 0.09); shorter LES relaxation duration after dry/water/syrup swallows (P = 0.0001, P < 0.0001, P = 0.0001, respectively); higher amplitude of proximal contrac- tions after dry/water/syrup swallows (P = 0.008, P = 0.01, P = 0.04); tendency for longer duration of distal contractions after dry/water/ syrup swallows (P = 0.07, P = 0.04, P = 0.09); lower velocity of distal contractions after dry/water/syrup swallows (P = 0.006, P = 0.09, P = 0.02); and higher incidence of multi-peaked contractions after dry/water/syrup swallows (P = 0.03, P = 0.0001, P < 0.0001).