The objective of our study was to explain the histopathological changes of monodon baculovirus (MBV) in hepatopancreas and midgut tissues of the cultured Penaeus vannamei. Five-hundred and forty juvenile of P. vannamei with average size of 7.99±0.54 g and 3600 post larvae 10-15 were distributed to 18 glass aquariums (50×50×60cm) with 100L well aerated water per each aquarium as water borne MBV (group A) and food borne MBV (Group B) and one control group (C), in triplicates. Also, 3600 post larvae were dedicated for water borne exposure (D) based on one time immersion exposure in 24 h without water exchange and the untreated group was studied as control in triplicates. The specific pathological sign of MBV was observed as a multiple intranuclear eosinophilic occlusion bodies (OBs) in hepatopancreas and midgut tissues. Our result indicates that the severity of the MBV infection is more considerable in post larvae than juvenile stage and confirms that MBV can be an invasive pathogen for shrimp culture industry in Iran.