Fifty-three children with chronic idiopathic constipation, 32 with fecal soiling and 21 without soiling, were investigated by total gastrointestinal transit time (TGITT) and anorectal manometry (ARM). TGITT and ARM were also performed, respectively, in 46 and 32 healthy subjects. Twenty-two of the 32 children with soiling were successfully managed by medical treatment and toilet training. TGITT was significantly longer in all constipated children than in normal children. Furthermore, some parameters of anorectal motility (threshold volume, amplitude of threshold inhibitory anal reflex) of the patients differed markedly from those measured in controls. Rectal compliance was significantly higher in children with fecal soiling than in children with constipation without soiling and healthy controls. In the successfully treated children, soiling disappeared, TGITT normalized, and anorectal variables changed significantly. It is concluded that TGITT is useful in assessing the degree of constipation. Electromanometry of the anorectum is of great help in the diagnosis of functional constipation by excluding aganglionosis; furthermore, it provides additional information allowing better understanding of the mechanisms involved in functional constipation in children.