Abstract: In an attempt to explain the scientific basis for the medicinal and nutritional benefits of the leafy vegetable, the phytochemical constituent, antioxidant and antimicrobial activity were assessed. In this study, dried leaves of Ocimum gratissimum were extracted with rectified spirit and the extracts were subsequently analyzed for their phytochemical constituent, antioxidant property as typified by its total phenol content, free radical scavenging ability and reducing power, as well as the ability of the extracts to inhibit the growth of some clinically isolated Enterobacterioceae and some fungi. The result of the study revealed that Ocimum gratissimum extract contains tannin, saponin, anthraquinone, alkaloid and glycosides, the total phenolic content of the extract was 3.6 g/100 g, while the reducing power and free radical scavenging ability were 2.4 OD700 and 51.2%, respectively. 1.0 mg mL-1 of the extract inhibited the growth of the following bacteria: Proteus sp. (3.4 mm), Pseudomonads aeruginosa (5.0 mm), Shigella dysentria (29.0 mm) and Staphylococcus aureus (18.0 mm) and fungi [Saccharomyces cerevisae (9.0 mm) and Candida albicans (13.0 mm)]. Furthermore, the inhibition of both the fungi and bacteria were found to be dose-dependent. However, same concentration of the extract will not inhibit the growth of the following bacteria: Klebsiella sp., Escherichia coli and some fungi namely; Penicillium sp., Aspergillus fumigatus, Fusarium solani and Aspergillus flavus. It could therefore be concluded that part of the reasons for the use of Ocimum gratissimum leaves in folk medicine against gastrointestinal disorders and haemorrhoids could be as result of its antioxidant and antimicrobial property which is hinged on the array of pharmacological active phytochemicals present in the vegetable leaves.