The density of the sympathetic innervation and enteric neuron number in Auerbach's plexus has been investigated by glyoxylic acid histofluorescence and by enzyme histochemistry respectively, in the jejunum of adult rats whose mothers had undergone dietary restriction during the last two weeks of pregnancy. Enteric neuron numbers were reduced by 27% and the sympathetic innervation was more sparse, less regularly arranged and showed less fluorescence in the undernourished rats compared to control groups. These results indicate that the effects of maternal undernutrition on the sympathetic and enteric nervous systems are long lasting in the offspring and also that the terminal parts of the sympathetic neuron, as well as the cell body, are susceptible to a nutritional insult.