The aim of this study was to determine blood levels of malondialdehyde (MDA), reduced glutathione (GSH), ceruloplasmin and vitamin C, and the percentages of peripheral blood T-lymphocytes using the alpha-naphthyl acetate esterase (ANAE) method on Mallard (Anas platyrhynchos), Muscovy (Cairina moschata) and Pekin (Anas domestica) ducks. Blood samples were obtained from 8 adult ducks of each breed. The serum levels observed in Mallard, Muscovy and Pekin ducks respectively were 0.8, 1.07 and 1.3 nmol MDA per ml; 77.4, 66.9 and 78.7 mg GSH per 100 ml; 23.9, 26.1 and 24.1 mg ceruloplasmin per 100 ml; and 0.50, 0.52 and 0.70 mg vitamin C per 100 ml. The percentage of the ANAE (+) lymphocytes was 57.9%, 54.8% and 55.1% in Mallard, Muscovy and Pekin ducks, respectively. In this study, blood levels of lipid peroxidation and nonenzymatic antioxidants in the Mallard, Muscovy and Pekin ducks were determined.