We evaluated the efficacy and tolerance of the Conveen® anal plug in children with spina bifida or anal atresia with persistent fecal incontinence necessitating diapers despite bowel management. Seven 4 to 12-year-old patients with high congenital imperforate anus and 9 who were 6 to 13 years old with spina bifida, no mental retardation and no involuntary urine loss on clean intermittent catheterization were included in the study. During a prospective, 6-week crossover descriptive study after a test period to find the most comfortable plug with a diameter of 37 or 45 mm patients and parents completed a diary with the number of soiling episodes, stool frequency, stool consistency and the number of diapers used during 3 weeks without and with the plug, respectively. They provided a final assessment of the device. Two of the 7 patients with congenital imperforate anus discontinued use because of pain and discomfort, 1 had a decrease in soiling episodes and 4 achieved full continence and needed no diapers while using 2 plugs daily (range 1 to 4). All patients preferred the smaller plug. Two of the 9 patients with spina bifida always lost the plug within 1 hour after introduction, 5 had a decrease in soiling episodes but continued to need diapers and 2 achieved full continence using 2 plugs daily (range 1 to 4). All patients preferred the larger plug. The Conveen® anal plug is an adjuvant treatment option for fecal incontinence in children with congenital imperforate anus or spina bifida, enabling a minority to stop using diapers. The Conveen® anal plug is not a universal solution for fecal incontinence problems in these patients.