The kinetics of metoclopramide and the effects of haemodialysis on metoclopramide kinetics were examined in eight uraemic subjects 1 h and 24 h prior to the onset of dialysis. In spite of the relatively minor contribution of renal clearance to total body clearance in normals, metoclopramide kinetics were substantially altered in uraemia. The total body clearance was decreased by 2-4 fold, terminal elimination half-life proportionately increased, while the volume of distribution appeared to be unaffected compared with that previously demonstrated in normal healthy subjects. Haemodialysis does not appear to be effective in removing metoclopramide from the body and metoclopramide clearance subsequent to dialysis is unaltered. The kinetic parameters in the uraemic subjects are not significantly different between drug administrations 1 or 24 h prior to the time of onset of haemodialysis. Following kidney transplantation, in one subject, there appeared to be a rapid return to apparently normal kinetics from the uraemic state.