Abstract: Five cassane diterpenes were isolated from the 95% ethanol extract of the seeds of Caesalpinia bonduc (Leguminosea) by a combination of various chromatographic methods, including silica gel, Sephadex LH-20, and semi-preparative HPLC. On the basis of spectroscopic techniques, their structures were identified as 3β-acetoxy-cassa-12,14(17),15-trien-7β-ol (1), caesalmin C (2), caesall E (3), caesalpinin MJ (4), and 1-deacetylcaesalmin C (5). Among them, compound 1 is a new compound and 2, 4, 5 were isolated from the plant for the first time.