Serial chest radiology and echocardiography were performed in seven patients undergoing chronic haemodialysis who developed pericarditis. Echocardiography was helpful in making an early diagnosis of a pericardial effusion in the absence of specific clinical or radiological signs of an effusion. It also enabled changes in the thickness of a pericardial effusion to be detected, which was of value when clinical features suggestive of cardiac tamponade occurred during dialysis, and showed that the effusion could increase in size despite the use of regional heparinisation for dialysis. Resolution of a pericardial effusion could be defined accurately using echocardiography, whereas this was not possible clinically or radiologically. It is concluded that serial echocardiography is a good method of monitoring a pericardial effusion in dialysis patients.