Ochratoxin A (OTA) is a mycotoxin produced by the fungi Aspergillus and Penicillium. It occurs naturally in many products of plant origin and in animals because of the carry-over from feed to meat or milk. Ochratoxin A has nephrotoxic, carcinogenic, hepatotoxic, neurotoxic, and genotoxic properties. Data on ochratoxin concentrations in blood or serum from patients with different kidney disorders are available for several European countries, as well as for Africa and Asia. In this study, we determined OTA concentrations in serum samples from chronic renal failure patients receiving dialysis and from healthy controls, collected in central Poland. Ochratoxin A was analyzed after extraction and purification using immunoaffinity columns by liquid chromatography with fluorescence detection (limit of quantification: 0.1 ng/mL) in 88 patients and 16 healthy volunteers. The dialysis group consisted of 40 women and 48 men aged between 23 and 85 years. The mean OTA concentrations were 0.75 ng/mL (maximum 2.78 ng/mL) in dialysis patients and 0.70 ng/mL (maximum 1.44 ng/mL) in healthy controls. The mean concentrations in patients treated by dialysis were 0.76 and 0.74 ng/ml for women and men, respectively (maximum 2.53 ng/ml for women and 2.78 ng/ml for men). Statistical analysis using Student's t-test showed no statistically significant differences between the control group (non-dialysis patients) and all dialysis patients.