Congenital absence of the vagina is rare and occurs as a result of aplasia of the Müllerian ducts (46,XX) or complete androgen insensitivity syndrome (AIS--46,XY). Both syndromes are associated with normal female external genitalia and these patients are raised as females. These children are usually treated during adolescence with chronic dilatation of the shallow vaginal introitus (pressure tube technique) or by skin graft vaginoplasty (McIndoe procedure). Neither of these procedures is entirely satisfactory, as both may lead to neovaginal stenosis, inadequate length, poor lubrication, or all three. We have recently modified the operation first described by Baldwin in which a loop of sigmoid colon or small bowel is isolated, closed at one end, and brought down on its vascular pedicle as a neovagina and anastomosed to the hymenal ring. We have performed this operation on four adolescents (mean age, 15 years) and two infants (aged 4 days and 14 months) with excellent results (mean follow-up, 7.5 years for the adolescents and 1.8 years for the infants).(ABSTRACT TRUNCATED AT 250 WORDS)