Swietenia mahagoni (L.) Jacq. belongs to the Meliaceae family and it is native to the West Indies. It was introduced to India in 1975 and now grown in any parts of India. Biological activities of the plant are due to the abundance of phenolic compounds including different terpenoids and limonoids. The plant possesses various secondary metabolites which are responsible for its anti-bacterial, anti-fungal, anti-malarial, anti-diabetic antioxidant, anti-ulcer, anti-viral, anti-diarrhoeal, anti-pyretic and antiinflammatory properties. This antimicrobial activity encouraged to work on identification of phytochemical and antimicrobial investigation of this herbal plant. The seeds and barks of Swietenia mahagoni is subjected to phytochemical screening for secondary metabolites and disk diffusion method for its antimicrobial activity against standard MTCC strains, two bacteria namely Staphylococcus aureus (gram+) (MTCC no. 6908), Escherichia coli (gram-) (MTCC no. 77) and one fungus Aspergillus niger (MTCC No.1344) were used for the study. The qualitative phytochemical tests reveal the presences of phytocompounds including alkaloids, terpenoids, tannins, and glycosides as major active constituents. The seed and bark extracts exhibit positively significant antimicrobial activity against the standard strains. The fungal activity was good in seed extracts, and bacterial activity was significant in bark extracts.