The effect of uraemia on protein glycation was studied by measuring glycated albumin and fructosamine in 50 non-diabetic dialysis patients (31 continuous ambulatory peritoneal dialysis, CAPD, 19 haemodialysis). After correction for serum albumin concentration, glycated albumin (g/100 g) was increased in the haemodialysis group (1.94 +/- 0.40) compared with both CAPD patients (1.46 +/- 0.37; p < 0.001) and controls (1.52 +/- 0.29; p < 0.001), but did not differ between CAPD patients and controls (p > 0.05). Serum fructosamine, corrected for either serum albumin or total protein concentration (mumol/100 g), was raised in CAPD (828 +/- 90, 386 +/- 41, respectively) and haemodialysis patients (802 +/- 123, 391 +/- 42, respectively) compared with controls (609 +/- 69, 332 +/- 27, respectively; p < 0.0001 in all cases), but did not differ between the two dialysis groups (p > 0.05). A single haemodialysis cycle had no effect on the measurement of glycated albumin or fructosamine (p > 0.05). The results confirm that glycated protein levels are generally raised in dialysis patients. In CAPD patients, altered albumin metabolism resulting from large peritoneal losses is likely to have caused a decrease in the amount of albumin glycated, an effect less apparent on the concentration of fructosamine because of the additional contribution of glycated globulins.