The aim of this study was to investigate the changes in the blood serum levels of some biochemical parameters, lipid-soluble vitamins and trace elements in the calves naturally infected with Giardia spp. in Van region, before and after treatment with orally 20 mg/kg(-1) albendazole three successive days. Serum samples were analyzed for biochemical parameters and some vitamins. In the infected animals, concentrations of creatinine, amylase levels were lower (p<0.05). Glucose, urea, total protein, AST, ALT, sodium, potassium, retinol and a-tocopherol levels were seen significantly higher in the after treatment group (p<0.05). There was no statistically significant difference in the concentration of total bilirubin, chloride and vitamin D-3 between groups. All the animals were not encountered cysts or trophozoites of Giardia at the end of the treatment. The results of this study would suggest albendazole to be 100 % effective against giardiasis in all of the calves in Van region.