Bursera simaruba (L.) Sarg. leaves hexane extracts display anti-inflammatory activity on the adjuvant-carrageenan-induced inflammation in rats. In order to isolate and identify the active compounds of the hexane extract, we performed a preliminary phytochemical study and a bioassay-directed fractionation using the carrageenan-induced paw oedema test in mice. From the nine fractions (A-I) obtained, of an initial chromatographic separation, fractions A and E (doses equivalents to 1.50 g dry plant/kg body weight) showed the strongest anti-inflammatory activity comparable to that of the reference drug phenylbutazone (80 mg/kg). The isolation and characterization of 3-methylene-7,11,15-trimethylhexadec-1-ene (neophytadiene) (1), ergost-5-en-3beta-ol (2), 24S-stigmast-5,22E-dien-3beta-ol (3), 24S-stigmast-5-en-3beta-ol (4) and alpha-amyrin (5), from these fractions is reported.