Ochratoxin A is a fungal toxin produced by Aspergillus and Penicillinium. These Fungi oftenly contaminate plant-derived products, and can generate deleterious toxic effects in man. In this study, ochratoxin A was determined in human serum samples collected in Tunisia, using high performance liquid chromatography (HPLC) and fluorescence detection. The samples were collected from healthy subjects (n = 105) as well as from patients with various kidney disorders. Five different kinds of kidney disorders were represented: transplanted subjects (27), patients with Chronic Interstitial Nephropathy (22) of known etiology, Chronic Vascular Nephropathy (26), Chronic Glomerular Nephropathy (26) or Chronic Interstitial Nephropathy (30) of unknown etiology. Mean concentrations of ochratoxin A in the healthy group was 0.49+/-0.79 ng/mL. The highest mean concentration of ochratoxin A was found in group of Chronic Interstitial Nephropathy of unknown etiology 1.25+/-1.22 ng/mL. Significant differences were also observed according to the geographic origin of healthy subjects and nephropthic patients within Tunisia.