Besides the known compounds longistylines C (1), D (2), and 3,5-dimethoxystilbene (5), five new prenylated stilbenes, named chiricanines A-E (3, 4, 6-8), have been isolated from the root bark of Lonchocarpus chiricanus. Their structures were resolved on the basis of spectrometric methods including H-1, C-13, and 2D NMR experiments and mass spectrometry. Compound 3 was the only prenylated stilbene to demonstrate antifungal effects against Cladosporium cucumerinum. Four of the isolated compounds showed toxic properties against larvae of the yellow fever-transmitting mosquito Aedes aegypti. Compound 5 was found to be as potent as rotenone in larvicidal dilution tests.