Purpose: This systematic review determines the best known form of biofeedback (BF) and/or electrical stimulation (ES) for the treatment of fecal incontinence in adults and rates the quality of evidence using the Grades of Recommendation, Assessment, Development, and Evaluation. Attention is given to type, strength, and application mode of the current for ES and to safety. Methods: Methods followed the Cochrane Handbook. Randomized controlled trials were included. Studies were searched in The Cochrane Library, MEDLINE, and EMBASE (registration number (PROSPERO): CRD42011001334). Results: BF and/or ES were studied in 13 randomized parallel-group trials. In 12 trials, at least one therapy group received BF alone and/or in combination with ES, while ES alone was evaluated in seven trials. Three (four) trials were rated as of high (moderate) quality. Average current strength was reported in three of seven studies investigating ES; only two studies reached the therapeutic window. No trial showed superiority of control, or of BF alone or of ES alone when compared with BF + ES. Superiority of BF + ES over any monotherapy was demonstrated in several trials. Amplitude-modulated medium-frequency (AM-MF) stimulation, also termed pre-modulated interferential stimulation, combined with BF was superior to both low-frequency ES and BF alone, and 50 % of the patients were continent after 6 months of treatment. Effects increased with treatment duration. Safety reporting was bad, and there are safety issues with some forms of low-frequency ES. Conclusions: There is sufficient evidence for the efficacy of BF plus ES combined in treating fecal incontinence. AM-MF plus BF seems to be the most effective and safe treatment. Key Messages: • The higher the quality of the randomized trial the more likely was a significant difference between treatment groups. • Two times more patients became continent when biofeedback was used instead of a control, such as pelvic floor exercises. • Two times more patients became continent when biofeedback plus electrical stimulation was used instead of biofeedback only. • Low-frequency electrical stimulation can have adverse device effects, and this is in contrast to amplitude-modulated medium-frequency electrical stimulation. • There is high quality evidence that amplitude-modulated medium-frequency electrical stimulation plus electromyography biofeedback is the best second-line treatment for fecal incontinence.