We investigated the efficacy of biofeedback treatment and evaluated anorectal factors that might be responsible for persistence of chronic constipation with or without encopresis in a group of 38 children with abnormal contraction of the pelvic floor during straining and persistence of chronic constipation with encopresis after conventional treatment. Nine children were unsuccessful in learning to relax the pelvic floor during straining with biofeedback treatment, and one patient had contraction of the pelvic floor on follow-up despite successful biofeedback treatment; none recovered. Twenty-eight children were able to relax the pelvic floor on follow-up; 14 recovered and 14 did not recover from chronic constipation. Nonrecovered patients who learned to relax the pelvic floor had significantly decreased rectal and anal responsiveness to rectal distension as compared to recovered patients during the initial and follow-up anorectal manometric study. Psychological factors such as social competence and behavior problems did not appear to be responsible for recovery or nonrecovery from chronic constipation and encopresis.