Lasia spinosa (L.) Thwaites is a widely used ethnomedicinal plant in Bangladesh. In this study, we investigated phenolic contents, volatile compounds and fatty acids, and essential oil components of extracts prepared from aerial parts of the plant. The main volatile compounds were methyl ester of oleic acid, palmitic acid and stearic acid as determined by GC/MS. Phenolic contents of the extracts were determined qualitatively and quantitatively by HPLC/TOF-MS. Six phenolic compounds (syringic acid, morin, gentistic acid, 4-hydroxybenzoic acid, cinnamic acid, and apigenin) were found in the extracts. GC/MS analysis of steam distilled essential oil showed camphor, alpha-pinene and delta-3-carene as the main constituents. In DPPH radical scavenging assay, the highest free radical scavenging activity was observed for the methanol extract with an IC50 value of 0.48 +/- 0.04 mg/mL, whereas, in metal chelating activity on ferrous ions (Fe2+) assay, the highest chelating activity was observed for hexane extract (IC50 = 0.55 +/- 0.08 mg/mL). The extracts and essential oil were tested against five severe human pathogenic bacteria using disc diffusion assay and subsequent M IC values were also determined. All the extracts (except methanol extract) and the essential oil were found to possess potential antimicrobial activity with corresponding inhibition zone and minimum inhibitory concentration (MIC) ranging from 9-23 mm and 62.5-500 mu g/mL. This study has been explored the plant Lasia spinosa can be seen as a potential source of biologically active compounds.