Cardiac markers are more likely to be elevated in dialysis patients than in patients with renal failure not on dialysis. In this study, 31 patients (20 males, 11 females) undergoing chronic haemodialysis were enrolled. The effect of haemodialysis on cardiac troponin T (cTnT), I (cTnl), creatine kinase MB (CKMB) mass, CKMB activity and myoglobin assays was assessed by comparing pre- and post-haemodialysis determinations. After correcting for haemoconcentration, significant differences were observed (mean +/- SEM, pre- vs post-dialysis) for myoglobin (178.9 +/- 19.3 vs 225.0 +/- 28.4 ng/ml; p=0.006) for cTnT (0.111 +/- 0.028 vs 0.148 +/- 0.037 ng/ml; p=0.004), for CKMB mass (2,75 +/- 0.37 vs 2.59 +/- 0.37 ng/ml; p=0.000) and CKMB activity (14.8 +/- 0.9 vs 13.1 +/- 0.9 U/I; p=0.000) assays. Our study questions the reliability of cardiac markers in dialysis patients and suggests that the clinical threshold value and diagnostic efficiency of each assay needs to be validated. Although these differences exceeded clinical threshold values in only a few patients, serum markers of myocardial damage in dialysis patients should be interpreted with caution.