Prospective evaluation of 114 obese patients (96 women, 18 men) undergoing vertical banded gastroplasty over a 5-year period was undertaken. The age range was 17-58 (median 37) years, median weight 119.3 (range 79-216) kg, mean(s.d.) proportion of excess body-weight 104.1 (34.9) per cent and median body mass index (BMI) 44.8 (range 33.2-77.7) kg/m2. Three gastric outlet stoma circumferences were used: 5.5 cm (31 patients), 5.0 cm (28) and 4.75 cm (55). A total of 109 patients (95.6 per cent) were available for follow-up. At 1 year after operation, 54 patients (59 per cent) had lost greater than 50 per cent of excess body-weight. No patient lost less than 25 per cent of excess body-weight, and the median BMI was 32.5 (range 21.3-47.8) kg/m2. The operative mortality rate was zero, but three patients (2.6 per cent) with gastric leakage required surgical revision. Vertical banded gastroplasty is a relatively safe and simple procedure that produces significant and sustained weight reduction in the majority of morbidly obese patients.