Bacteria Vibrio spp. is the causative agent of disease in shrimp, in which the common diseases are acute necrotic syndrome (Acute hepatopancreatic necrosis syndrome - AHPNS) and white feces disease (white feces syndrome - WFD). The usage of antibiotics to treat diseases makes bacteria multi-resistant. A bacteriophage is a virus of bacteria that it has the ability to infect and kill bacteria. This research evaluates the efficiency of bacteriophages in the treatment of white leg shrimps (Litopenaeus vannamei) disease. After 24 hours of bacteriophage inoculation, the water in the culture tank changed from cloudy to clear. The density of bacteria in the water decreased clearly from 4,6x104 CFU/ml to 6,5x102 CFU/ml and after two days of phage inoculation, the bacterial density continued to decline to 3,3x102 CFU/ml. The results on shrimp samples were similar with the effect of bacteriophages, bacteria in the hepatopancreas of shrimps decreased from 2,3x103 CFU/individual to 1,1x102 CFU/individual. The activities and morphology of shrimp were clearly different when shrimps were infected and treated. Infected shrimps worked slowly, stopped eating, leaden, empty intestines, pale hepatopancreas. But after only two days of inoculation with bacteriophages, shrimp began to eat again, hepatopancreas also darker, intestines gradually filled. The hepatopancreas tissue samples of shrimps were infected by Vibrio parahaemolyticus, the cells had signs of peeling and falling into the lumen of the hepatopancreatic duct lumen and the phenomenon of melanization due to the blackening of blood cells around the necrotic area. After bacteriophage treatment, the stellate structure gradually recovered, the blood cells were not found around the tubules, in the lumen of the tubules reduced peeling cells and blood cells, the melanization was not observed. Based on these results, it can be recognized that phages are a biological solution to replace antibiotics in the disease prevention.