The total, albumin-bound, and alpha 2-macroglobulin-bound zinc concentrations in serum samples obtained from 20 haemodialysis patients have been measured. Blood leucocyte zinc contents were also determined. The total serum zinc concentrations in these samples were low, and in each case this was due to reduction in the zinc associated with albumin, although the concentrations of albumin itself were normal. There was no abnormality of the zinc bound to alpha 2-macroglobulin. These data demonstrate a disturbance of the plasma transport of zinc in haemodialysis patients which might be due either to a reduced affinity of albumin for zinc in uraemic subjects, or the result of zinc deficiency. The zinc contents of white blood cells were also significantly reduced, supporting the possibility that these patients were indeed zinc deficient.