An ethanol extract from Veratrum lobelianum Bernh. rhizomes showed larvicidal activity with LC50 values of 11.79 ppm and 89.9 ppm against rand 4 1 b instar larvae, respectively, at 24 h post-treatment. The extract also showed proportion not biting (PNB) value of 0.76 at 100 mu g/cm(2) against females of Ae. aegypti. Systematic bioassay-guided fractionation of V. lobelianum extract resulted in the isolation of five compounds that were identified as ethyl palmitate (1), ethyl linoleate (2), p-sitosterol (3), resveratrol (4) and oxyresveratrol (5) by GC-MS, H-1-NMR, and C-13-NMR techniques, comparison with literature data, and confirmation with authentic compounds. Compound 2 exhibited larvicidal activity with an LC50 value of 24.1 (22.0-26.2) ppm whereas 1 was inactive. B-Sitosterol (3) displayed the highest larvicidal activity with LC50 = 1.7 (1.3-2.3) ppm and LC90 = 5.1 (3.4-13.8) ppm. Compounds 4 and 5 had larvicidal activity with LC50 values of 18.5 (15.3-22.3) and 22.6 (19.0-26.8) ppm, respectively, and had an equivalent PNB values of 0.75 at 25 nmol/cm(2). In addition, 4 and 5 were explored for their human-based repellency against Ae. aegypti, attractiveness against male medflies Ceratitis capitata, and also evaluated against series of human carcinoma cells (A549, HEK293, HeLa, SH-SY5Y); however, no significant activity was found.