In the present investigation, the antioxidant, antifungal and antibacterial activities of Garcinia cambogia plant extracts were studied. Hot and cold of aqueous extracts of 5, 7.5 and10% (w/v) concentrations were used as a natural preservative beverage. These prepared extracts were used for evaluation of their antifungal (against Fusarium moniliforme and Aspergillus flavus) and antibacterial properties (against gram-negative bacterial strains, Escherichia coli and gram-positive bacterial strains, Bacillus cereus). Such materials have a high content of polyphenol compounds such as pyrogallol, catechin, catechol, epicatechein, chlorogenic and salycilic acid in addition to flavonoides and isoflavonoides compounds. Garcinia cambogia contains considerable amounts of water and fat soluble vitamins. Sensory evaluation of Guava nectar supplemented with Garcinia cambogia extracts (7.5 and10% w/v) as a natural preservative, showed no significant difference in taste, colour, texture, flavour and appearance compared with control. The data showed no microbial spoilage in guava nectar supplemented with different Garcinia cambogia (cold and hot) extract concentrations and control at zero time. After one and two weeks of storage nectar in the refrigerator showed an increase in total bacterial counts in the control, meanwhile, guava nectar containing Garcinia cambogia extracts (7.5% and 10%) cold and hot showed a slight increase in bacterial count. It could be concluded that Garcinia cambogia plants has high antioxidant, antibacterial, antifungal activity properties which have some beneficial effects on health and can be used as natural preservative substances in food and beverages.