Ochratoxin A (OTA) is a mycotoxin produced by secondary metabolism of several fungi belonging to the genera Aspergillus and Penicillium. OTA is potentially nephrotoxic, neurotoxic, immunotoxic and carcinogenic in several animal species and in humans. This toxin has been detected in several human food and animal feed. The aim of this study was to determine OTA in blood samples of healthy and affected by chronic kidney disease (CKD) dogs. CKD group showed higher incidence of OTA-positivity than healthy dogs (96 vs. 56%) and a significantly higher median value of OTA plasma concentration (0.008 vs. 0.144 ng/ml). No significant correlation was observed between OTA levels and creatinine values in CKD dogs. This is the first study regarding OTA detection in plasma samples of healthy and CKD dogs; the presence of this toxin is higher in nephropatic patients but is not yet clear, if it is correlated with progression of the disease.