The antimicrobial activity in vivo on oranges, dragon fruits and mangoes of essential oil from Curcuma Jonga L. derived by steam distillation was assessed. Orages and mangoes after preliminary treatment, were immersed in fungal and yeast solution with concentration about 10 exponent 5 CFU/ml. Fruits then were treated with crude turmeric oil at concentrations (v/v) of 0.5 percent and 1 percent (for oranges) and 2 percent (for mangoes). Specially for dragon fruits, 5 wounds per fruit were created, dripping 20 ul fungal solution into wounds, drying at room temperature and then the wounds were treated with 20 ul 0.5 percent turmeric oil. The fruits were kept at room temperature and 75-80 percent humidity. Results: after 7 days treatment, oranges infected with investigated fungi and yeasts were ruined, while no changes were observed in the variants treated with turmeric oil. Oranges treated with turmeric oil after 25 days preservation retained their colour and degree of hardness, meanwhile no-oil treatment fruits were grown black and dried. Experiments with mangoes revealed that after 5 days, variants infected with microorganisms were spoilled completely, the variants treated with turmeric oil were still fresh. The mangoes treated with turmeric oil can extend preservation time up to 10 days, while quarter control fruit (without infection and treatment by oil) was ruined. For dragon fruits, 100 percent fruits infected with fungi and without oil treatment were spoiled after 10 days at room temperature, ratio of ruined fruits decreased 50 percent in variants with oil treatment after fungi infection.