Apoptosis (programmed cell death) was identified in histological sections of brain and gut tissue of adult mice fed seed preparations from the cycad Lepidozamia peroffskyana. This form of cell death was also found at high levels in brain tissue from neonatal mice born from a cycad-fed mother. The discovery was made during re-appraisal of archival tissue from a study of toxic properties of L. peroffskyana. Ingestion of appropriately prepared food or medicine derived from another cycad, Cycas circinalis, is thought to be associated with several motor neurone and other neurodegenerative disorders of some Pacific island inhabitants. Apoptosis is cell death under gene control. From the present study, presence of apoptosis in brain tissue after cycad toxicity may provide a link between cycad ingestion and development of neurodegenerative disorders and may provide a novel explanation for localization of some neurodegenerative disorders, as some inhabitants may have a genetic susceptibility to apoptosis induced by cycad toxicity.