Twelve grossly obese patients who weighed 121 +/- 22 kg (mean +/- s.d.) had a free-floating 600 ml spherical intragastric balloon inserted per oesophagus and have been followed for 12-24 months. Nine patients lost up to 21 kg (11 +/- 6.4 kg) over 3 months after which they reached a plateau and then regained weight so that by 1 year only one patient had maintained her weight loss. Three patients could not tolerate the balloon owing to complete reflex inhibition of gastric emptying. Such marginal and temporary weight loss is of no value in the treatment of gross obesity.