Pathophysiologic mechanisms responsible for severe chronic constipation are poorly understood. In particular, most of the published studies have lumped together patients having different subtypes of constipation, with different and often conflicting results. We studied six patients complaining of severe idiopathic constipation and displaying homogeneous clinical and pathophysiologic features (i.e., patients with slow-transit type constipation) to evaluate their myoelectric spiking responses to food ingestion. Ten healthy subjects acted as controls. The constipated patients failed to show the increase in myoelectric spiking activity that was seen in controls immediately following the meals, suggesting the possibility of a neurogenic defect in this condition.