The purpose of this study was to prospectively investigate a consecutive patient series (N = 70) with anal sphincter insufficiency and compare the efficacy of biofeedback and electrostimulation as conservative treatment options. Forty patients were treated by biofeedback training, 30 patients by electrostimulation. Patients were not specifically selected for one or the other treatment. Success was evaluated by vector volume manometry, water infusion test, time until stoma closure and clinical incontinence scores. Resting and squeeze pressure and resting and squeeze vector volume all increased significantly after biofeedback training (P < 0.05 and < 0.001). Resting pressure and squeeze vector volume only were significantly improved by electrostimulation (P < 0.05 and < 0.01). The increase in squeeze vector volume was significantly greater in the biofeedback group (P = 0.03). The estimated median time period from commencement of training until stoma closure was 9 months in the biofeedback versus 21 months in the electrostimulation group. Biofeedback training is probably superior to electrostimulation in the conservative treatment of anal sphincter insufficiency, this needs to be confirmed in a randomized study.