Investigation of leaves from the shrub Piper tuberculatum for compounds that might serve as repellents to leafcutting ants has led to identification of three cinnamic acid derivatives. One has been characterized as a new piperidine epoxide, piplaroxide (1), while the other two were recognized as the known compounds piplartine (2) and demethoxypiplartine (3). Both piplaroxide and demethoxypiplartine demonstrated significant activity in a laboratory bioassay measuring repellency to the leafcutter ant Atta cephalotes.