Liquid enteral formulas are commonly used as a sole source of nutritional support of patients in hospital and community settings. Their effect on appetite has important consequences for dietary management of such patients and is likely to be affected by the formula composition. The aim of the present study was to compare appetite within healthy subjects consuming both a standard formula and one supplemented with pea-fibre (10 g/l) and fructo-oligosaccharide (FOS; 5 g/l) as a sole source of nutrition. Eleven healthy subjects consumed a standard formula or a pea-fibre/FOS formula as a sole source of nutrition for 14 d in a double-blind, cross-over trial. Appetite was recorded using standard 100 mm lines anchored at each end by a phrase denoting the most extreme appetite sensation. Consumption of the pea-fibre/FOS formula resulted in higher mean fullness (46 v. 37 mm, P=0.035), minimum fullness (13 v. 9 mm, P=0.024) and minimum satiety (12 v. 8 mm, P=0.012) compared to the standard formula. As there were no differences in macronutrient intake between formulas, these differences are likely to be due to supplementation with pea-fibre and FOS. The effect on appetite of the composition of an enteral formula, both with respect to nutrient content and functional components such as pea-fibre and FOS, may be an important aspect to consider in the dietary management of patients consuming enteral formula as a sole source of nutrition.