Objective. To compare the outcome of end-to-end approximation versus the overlap technique for primary repair of obstetric anal sphincter rupture (OASR) at 12 month follow-up. Design. Prospective, randomized controlled study. Setting. University hospital. Sample. One hundred and twenty-eight patients with grade 3b, 3c or 4 OASR were randomized; 119 (end-to-end 60, overlap 59) received the allocated treatment. We obtained information concerning fecal incontinence from 101 (85%) patients. Methods. The obstetric team on call performed the repairs. Wexner score, endoanal ultrasound (EAUS), and manometry were used to evaluate anal sphincter function at 12 months post-surgery. Main outcome measures. Primary outcome was incidence of solid stool leakage at least once a week. Secondary outcomes were flatus incontinence, Wexner score, external anal muscle defect examined by EAUS, and anal manometry results. Results. One patient in the end-to-end group and none in the overlap group reported leakage of solid stool once a week or more. Fourteen patients in the end-to-end group and 10 in the overlap group reported flatus incontinence (p = 0.48). Mean Wexner score was similar in both groups, 2.4 versus 2.2. One patient in the end-to-end group and none in the overlap group had a Wexner score >10 (severe anal incontinence) (NS). External sphincter defect was found in 2/46 in the end-to-end group compared to 0/41 in the overlap group (NS). Anal manometry findings were similar in both groups. Conclusion. The overlap repair was not superior to the approximation technique with regard to fecal incontinence at 12 months.