Background: Anal sphincter tears during vaginal delivery may result in serious sequel. Anal sphincter tears occur in approximately 2–19 % of all vaginal deliveries and are the most common precursor for faecal incontinence,1 however »occult« anal sphincter injury has been defined in 33 % of primiparous women following vaginal delivery.2 Methods: 31-year old primiparous woman received transfusion due to atony after delivery. Episiotomy, second degree perineal tear and vaginal tear were surgically corrected immediately after delivery. In the following days inability to control passing of liquid stools and flatulence together with stress urinary incontinence appeared. The complaint persisted. Ultrasound and EMG examination confirmed rupture of the external anal sphincter, which had been missed at delivery. Over a year after delivery the patient had a posterior colporraphy with surgical correction of external anal sphincter, which did not result in any clinical improve- ment. On follow-up ultrasound examination a hypoechoegenic area between the external sphincter and vaginal wall was detected. The patient was referred to The University Hos- pital in Graz, where the tear will be treated with autologous myoblast transplantation in a clinical trial. Conclusions: Treatment of a missed anal sphincter tear is complicated, expensive and unpleasant for the patient. Early detection with immediate appropriate surgical correction after delivery is most efficient, but it takes experience.