The aim of this research was to provide information on the immunomodulatory activity and protection striped catfish from pathogen after supplementation of levamisole. The effect of levamisole on the immune response of 480 striped catfish (Pangasianodon hypophthalmus) was evaluated. Fish were divided into 4 equal treatments and were fed with levamisole incorporated diet (300 mg kg^-1 feed) in 8 weeks, treatment 1 (control treatment), treatment 2 (fed with levamisole in 1^st, 2^nd week and 4^th, 5^th week), treatment 3 (fed with levamisole from 1^st to 4^th week), treatment 4 (fed with levamisole during 8 weeks). Results showed that the populations of total erythrocytes and leucocytes, neutrophils, monocytes and lymphocytes after sample collected in 4^th week were significantly, total erythrocyte and leucocyte of fish in treatment 2 was higher density than treatment 3, 4 and also higher than treatment 1 (control treatment) while neutrophils, monocytes and lymphocytes in treatment 2 lower density than treatment 3, 4 but it’s still higher density than treatment 1 (control treatment). Results of this experiment showed the safety of the dose and time effects of levamisole on striped catfish. The other findings indicate its efficiency as immunostimulant in improving the non-specific immune response of striped catfish to protect fish against bacteria.