To determine the effect of cordotomy on the function of the bladder during surgical correction of congenital kyphosis in myelomeningocele, we reviewed 13 patients who had this procedure between 1981 and 1996. The mean age of the patients at operation was 8.9 years (3.7 to 16) and the mean follow-up was 4.8 years (1.3 to 10.8). Bladder function before and after operation was assessed clinically and quantitatively by urodynamics. The mean preoperative kyphosis was 117° (52 to 175) and decreased to 49° (1 to 89) immediately after surgery. At the latest follow-up, a mean correction of 52% had been achieved. Only one patient showed deterioration in bladder function after operation. Eight out of the nine patients who had urodynamic assessment had improvement in bladder capacity and compliance, and five showed an increase in urethral pressure. One patient developed a spastic bladder and required subsequent surgical intervention. Cordotomy, at or below the level of the kyphosis, allows excellent correction of the structural deformity.