Filariasis is a vector-transmitted parasitic disease and has a worldwide spread.  This work aimed to study the effect of filariasis on hematology, blood chemistry and antioxidant status of adult buffaloes as well as efficacy of ivermectin in disease treatment. The present study was done on fifteen male buffaloes, 2-4 years old, (7 apparently health and 8 suffered from filariasis). The diagnosis was based on the clinical signs and presence of Microfilariae in wet smear. One animal died during treatment. Hematological results revealed hemolytic anemia associated with a significant decrease in erythrocytic count, hemoglobin concentration and packed cell volume. A significant increase in the total and differential leukocytic counts was recorded compared with the normal control.  Evaluation of blood chemistry of infested animals showed significant changes in liver and cardiac function, as well as antioxidant parameters. These parameters returned to the normal levels 21days post treatment with ivermectin. It could be concluded that filariasis induced hemolytic anemia, with alteration in antioxidant enzymes and liver and cardiac functions. Also ivermectin is effective in treatment of filariasis.