We examined the number of nerve cells of the myenteric plexus and the thickness of the smooth muscle in the small intestine in autopsy material of 6 young and 6 old persons. Neurons in the myenteric plexus have been visualised by a nonhistochemical method (Giemsa) in laminar preparations of the muscularis externa. Significant reductions of at least 34% in the number of neurons in the ganglia of the myenteric plexus of the old subjects were recorded in all regions of the small intestine, especially in the duodenum where the number of neurons decreased by over 38%. However, there was no significant correlation between nerve cell count and thickness of intestinal smooth muscle since no difference was found in thickness of intestinal smooth muscle between young and old subjects. The decrease in the neuron density with age could affect the potential of the enteric nervous system to influence control over several small intestinal functional parameters.