The effects of antireflux surgery on Barrett's oesophagus were studied. Fifty-six patients (45 men and 11 women of median age 48.5 (range 20-78) years) with histologically confirmed Barrett's oesophagus (greater than 3 cm in length) and gastro-oesophageal reflux underwent antireflux surgery. Symptoms were noted and patients underwent manometry and pH recording before and after operation, and annual flexible endoscopy. Fundoplication resulted in a significant improvement in lower oesophageal sphincter pressure (median (interquartile range (i.q.r.)) 8 (5-14) mmHg before operation versus 17 (11-22) mmHg after operation, P < 0.001). Twenty-four of the 56 patients had partial or complete regression of Barrett's oesophagus (median (i.q.r.) length 8 (3-18) cm before versus 4 (0-10) cm after operation, P < 0.001) but nine showed progression (median (i.q.r.) length 6 (3-11) cm before versus 10 (6-15) cm after operation, P < 0.01) (median follow-up 5.5 (range 2.0-10.5) years). Carcinoma developed in one patient. The length of Barrett's oesophagus was unchanged in 23 patients. Regression was more likely to occur in patients who underwent fundoplication with previous or concomitant vagotomy (chi 2 = 7.21, 1 d.f., P < 0.01) and in those with a good symptomatic result (chi 2 = 23.52, 1 d.f., P < 0.001).