An impairment can result in disability which can result in handicap. In Canada, disabilities have been based on 17 activities of daily living (ADL), nine of which may be due to massive obesity. Severe disability (SD) is inability to perform three or more of these ADL. During 1985, all patients with SD who underwent weight loss surgery were surveyed. Of 120 morbidly obese patients, 44 fulfilled the SD criteria. Effect of weight loss was observed over 5 years in 42 SD patients (initial mean body mass index 47.8 final 27.8), two being lost to follow-up. Disability became moderate (unable to do one or two of the ADL) in three, mild (difficult but able to perform) in 17, and disappeared in 22 patients. Two who regained lost weight redeveloped SD.