One fatty acid (1), one monoglycol ester (2), three diterpenes (3-5), four steroids (6-9), four triterpenes (10-13), three flavonoids (14-16), three anthraquinones (17-19) and one benzoquinone (20), were isolated from the methanolic extract of the leaves and trunk of Senna alata. These compounds were obtained by extensive silica gel chromatography and their structures elucidated by 1D and 2D nuclear magnetic resonance (NMR) as well as comparison with literature data. Compounds (2-4) have been reported for the first time from this species. Some isolated compounds and methanolic crude extract of leaves and trunk were screened in vitro for their antimicrobial activities. Kaempferol (16) exhibited strong activity against all the tested strains, with MIC values varying from 15.5 to 31.2 µg/mL, emodin (18) was active with a strong activity (7.8 µg/mL) exhibited on Pseudomonas aeruginosa. The trunk crude extract showed a strong activity with MIC values varying from 15.6 to 62.5 µg/mL. Manuscript profile