Neurolathyrism is a degenerative disorder due to an excessive consumption of Lathyrus sativus (LS) seeds, which contain the neurotoxic amino acid beta-N-oxalylamino-L-alanine. In this study, a population of Wistar rats was fed a diet with LS seeds up to 8 months. Two control groups were chosen, one receiving standard food and the other Cicer arietinum seeds (a nontoxic legume). At the end of the dietary period, the groups previously fed the seeds were switched to standard food for 1 month (wash-out). All animals were submitted to a neurological examination and observed in an open-field situation before, during the diet (at 4 and 8 months), and finally after wash-out. Neither LS-fed rats nor controls ever showed neurological deficits. By contrast, in an open-field the activity was significantly increased in the LS-eating rats at both the 4th and 8th month. The effect was indeed reversible, since it disappeared after the wash-out. It is suggested that the enhanced open-field activity seen in the LS group might indicate a reversible excitable status. However, there is no evidence at present that the behavioral changes described represent a marker of neurodegeneration in this animal species.