We present a new method for the measurement of the anorectal muscle complex. We studied 40 children with anorectal malformation (14 low and 16 high). Taking the perineal TAC with a rectal probe and quotient called "C": [formula: see text] A "C" value less than 0.31 indicates little development of the anus muscle complex. In 10/26 patients with high malformation, "C" was less than 0.31. All of these patients had fecal incontinence.