Natural products with medicinal value are gradually gaining importance in clinical research due to their well-known property of no side effects as compared to drugs. Aegle marmelos (L.) Correa (Rutaceae) commonly known as "bael" in Nepal and India, is a valuable medicinal plant and is considered sacred by the Hindus. It is used to cure several diseases in the Indian traditional medicine system of Ayurveda and has had similar uses among many ethnic communities residing in Indian subcontinent for over 5000 years. Its leaves, bark, stem, fruits and seeds have been used for various medicinal purposes. Recently the discovery of active components from the plant and their biological function in disease control has led to active interest in the plant across the globe. The aim of the present study was to evaluate physicochemical, qualitative and quantitative phytochemical analysis and in vitro antioxidant activities of leaves of Aegle marmelos collected from local areas of Sonipat, Haryana. The different physicochemical parameters were evaluated as per standard protocols with some modifications. Qualitative analysis of various phytochemical constituents and quantitative analysis of total phenolics and flavonoids were determined by the well-known test protocol available in the literature. Quantitative analysis of phenolic and flavonoids was carried out by Folins Ciocalteau reagent method and aluminium chloride method respectively. The In vitro antioxidant activity of methanolic extract of the leaves was assessed against DPPH and hydrogen peroxide scavenging assay method using standard protocols. The results obtained from the preliminary phytochemical screening of the methanolic extract of Aegle marmelos revealed the presence of carbohydrates, alkaloids, terpenoid, flavonoid, phenol, saponins and protein as major components. In petroleum ether extracts, only saponins are present. The total phenolics content of leaves methanolic extract was (84.5mg/100mg), followed by flavonoids (69.5mg/100mg). The activities of methanolic leaves extract against DPPH and hydrogen peroxide scavenging assay method were concentration dependent. The diverse array of phytochemicals present in the plant thus suggests its therapeutic potentials which may be explored in drug manufacturing industry as well as in traditional medicine.