A periodic motor activity, named the rectal motor complex, has been recently described in the healthy human rectum. We studied the rectal contractile activity for 24 h by a low compliance manometric system in a group of 10 women with slow transit constipation. Analysis of the 24-hour manometric recordings showed that these subjects: (1) had overall scarce rectal motility; (2) display few rectal motor complexes (average, 3.3 +/- 1.3/subject/24 h) which are irregularly distributed over time, and (3) respond weakly to ingestion of a standard meal (average duration of the motor response 19 +/- 6 min). The observations suggest that an underlying neuropathic process may be involved in the pathogenesis of the impaired rectal motility in patients with slow transit constipation.