Essential oils are complex mixtures of biologically active substances used since a long time as flavouring agents and constituents of number of commercial products. Currently,their importance is more highlighted due to their increasing demand for food, cosmetics and pharmaceutical industries. Recent scientific literature revealed the antimicrobial, antifungal and antioxidant potential of essential oils. In the present study, some sweet Basil(Ocimum basilicum) species of Labiatae family were screened for the isolation of essential oils.The hydro-distilled essential oils were characterized for their physic-chemical and biological activities.GC and GC-MS analysis of the chemical constituents of the isolated oils mainly revealed the presence of monoterpene hydrocarbons, sesquiterpene hydrocarbons, oxygenated monoterpenes and oxygenated sesquiterpenes. The investigated essential oils exhibited good antioxidant, cytotoxic and antimicrobial activities as measured by different in-vitro assays and experimental models.The variations in the yield,chemical composition and biological activities of most of the essential oils investigat in the present study with respect to species was sugnificant