This chapter discusses the practical use of biofeedback, including the instruments utilized and its evidence base, in functional gastrointestinal disorders (FGIDs). Biofeedback is a behavioural therapy using 'operant conditioning' techniques, including reinforcement with verbal instruction and instrumental stimuli, to modify breathing, intraabdominal pressure and/or pelvic floor muscle strength and coordination. Biofeedback has an established role in number of FGIDs, including dyssynergic defaecation, slow transit constipation and faecal incontinence, and limited evidence in irritable bowel syndrome (IBS), levator ani syndrome and upper FGIDs. Instruments utilized for biofeedback include manometry, electromyogram (EMG), rectal balloons, ultrasound, digital guidance or visual feedback techniques. Dyssynergic defaecation is defined as a paradoxical contraction or failure of pelvic floor muscle relaxation during defaecation. The use of biofeedback in dyssynergic defaecation has a substantial evidence base, consisting predominantly of uncontrolled trials and small randomized controlled trials. Faecal incontinence is defined as the involuntary loss of liquid or solid stool leading to social or hygiene problems.