Melastoma malabathricum L. (Malay name: Sendudok) is a plant widely used in traditional medicine of Malaysia and other Southeast Asian countries but little is known about its chemical constituents. This study reports the extraction of three classes of compounds, namely, triterpenoids, glycolipids and flavonoids from the leaves and flowers of this plant, and the purification of these compounds utilizing various chromatographic techniques and crystallization. The purified compounds were characterized by chemical and spectral analyses such as IR, UV, EI-MS, GC-MS, MALDI-TOF-MS and 1D- and 2D- NMR. Antibacterial activity of the different solvent extracts as well as the isolated constituents were assayed using the agar diffusion method. This study should be of interest to natural product chemists as well as practitioners of traditional medicine.