ABSTRACT Serranp, Elizabeth G. May 2023. PHYTOCHEMICAL AND ANTIBACTERIAL ACTIVITIES OF GIANT BOLO BAMBOO (Gigantochloa levis) SHOOT EXTRACT AGAINST GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA. BACHELOR OF SCIENCE IN BIOLOGY. Pampanga State Agricultural University. Adviser: Sharmane Y. Villanueva, M.Sc. Finding new, effective, and natural sources of potential therapeutic products is essential in modern times where health is prioritized and microbial resistance outbreaks are widely recognized in society. The study explored the phytochemicals using Thin-Layer Chromatography and antibacterial activities of the bamboo shoots extract of Giant bolo (Gigantochloa levis), a native bamboo species in the Philippines, against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria using Kirby-Bauer method on Mueller Hinton Agar. The extract exhibits secondary metabolites namely flavonoids, steroids, phenols, tannins, alkaloids, anthraquinones, anthrones, higher alcohols, and essential oils. The antibacterial activity of Giant bolo exhibited a significant difference (P-value =0.000) in varying concentrations against S. aureus and E. coli. At a concentration of 50 and 500 mg/ml, S. aureus showed antibacterial activity with mean zones of inhibition of 7.6667 mm and 14.3333 mm, respectively. E. coli showed activity with a mean zone of inhibition of 1 1.6667 mm in 500 mg/ml. The results of the study implicate that this plant could potentially be used as an antibacterial agent and in other medicinal applications.