The use of the resin of Virola elongata as an arrow poison was investigated. Aqueous and methanolic extracts of the dried bark were not observed to have toxic effects when administered intraperitoneally to mice. In an attempt to determine if the hallucinogenic indole alkaloid constituents of the bark, which form the basis for the alternate use of this material as a ceremonial snuff, could also be responsible for its use as an arrow poison, alkaloidal and non-alkaloidal extracts were compared with respect to their behavioral effects on mice. The non-alkaloidal extract was more effective in producing an observable alteration in behavior. This consisted of a marked reduction in spontaneous locomotor activity. The extract was fractionated and 13 of the major constituents assayed for their ability to reduce spontaneous locomotor activity. Most of this biological activity of the extract was attributable to the presence of the bis-tetrahydrofuran lignans, episesartemin, sesartemin, epi-yangambin and yangambin. Each of these compounds was also observed to reduce isolation induced aggression when administered to mice.