The most common cause of childhood fecal incontinence is constipation, also called overflow fecal incontinence. Constipation- mediated fecal incontinence requires comprehensive treatment. Biofeedback is a technique that can be mastered by children to control anal muscles. However, biofeedback therapy for overflow fecal incontinence has not been effective than conservative treatment in children. Presently, an eight-year-old boy visited our hospital for daily fecal incontinence that had persisted after enteritis three years previously. Pelvic floor dyssynergia was diagnosed by anorectal manometry. Two kinds of biofeedback therapy directed at constipation and incontinence were applied alternatively in the absence of drugs. Paradoxical contraction was much improved after four constipation protocol biofeedback sessions and high squeezing pressure was maintained after seven incontinence protocol biofeedback sessions. Soiling frequency quickly decreased from 4-5 times daily to less than once per week after nine constipation protocol and seven incontinence protocol biofeedback sessions. Ultimately, the defecation pattern normalized. Two additional constipation protocol biofeedback sessions applied to a child due to assumption that children have low learning ability. Two years following the biofeedback sessions, no anorectal problems have recurred and school life is uneventful. This case demonstrates that pelvic floor dyssynergia in children can be successfully treated without the use of drugs by modified and flexible biofeedback therapy.