In the present study the occurrence of ochratoxin A in blood serum from slaughter pigs in Upper Austria was determined. The samples were collected in the period from September until November 2001. As analytical method a competitive enzyme immunoassay, RIDASCREEN® Ochratoxin A (R-Biopharm GmbH, Germany) was used to detect the concentrations of ochratoxin A quantitatively. The representative sample was obtained by the number of slaughter pigs in Upper Austria in the year 2000 concerning the ochratoxin A concentration limit. An increased level of 2 percent of the ochratoxin A limit was estimated. In this study the concentration limit was referred to the Danish legislation limit (25 µg ochratoxin A/kg in the kidney). A total of 228 samples were collected in 10 different slaughter-houses. Only 43 (18,86 %) samples were negative. Positive samples were 185 (81,14 %) but 4 of them displayed ochratoxin A levels above 1.000 ng/l with a maximum of 1.891,52 ng ochratoxin A/l serum. The results showed that the concentrations of ochratoxin A in all samples analysed were below the threshold level. Between the slaughter-houses the ochratoxin A levels were significantly different.