It is unknown if abnormal anal sphincter function as assessed by anorectal manometry is still present years after resolution of chronic constipation and encopresis. Twenty healthy controls, 12 children with constipation but no encopresis, and 20 children with chronic constipation and encopresis underwent anorectal manometric testing, using intraluminal pressure transducers and a balloon for rectal distention. Anorectal measurements were repeated in the 20 constipated and encopretic children 2.5-4 yr after treatment began; 11 children had recovered for at least 1 yr. The mean values of anal resting tone and of anal pull-through pressure were lower in the constipated and encopretic children than in the 20 control children (p less than 0.003). Percent relaxation of the rectosphincteric reflex after rectal distention of 30 and 60 ml was lower in constipated children with and without encopresis than in controls (p less than 0.003), whereas the means of rectosphincteric reflex threshold were comparable in the three groups of children. Three years after initiation of treatment with milk of magnesia, high-fiber diet, and bowel training techniques, the mean values of anal resting tone, anal pull-through pressure, and percent relaxation of rectosphincteric reflex remained significantly lower in both recovered and nonrecovered constipated and encopretic patients compared with controls. It was suggested that the underlying cause of chronic constipation is the decreased ability of the internal anal sphincter to relax with rectal distention, and the hypotonia of the anal canal is responsible for the encopresis. Abnormal anorectal functions were still present years after cessation of treatment and recovery and put the recovered patient at risk for recurrence of chronic constipation and encopresis.