Abstract The usefulness of a paediatric fibre containing sip feeds specifically formulated for paediatrics has not been evaluated. In an open, prospective, parallel study the efficacy, safety and tolerance of a paediatric fibre-containing sip feed designed for children weighing 8–20 kg (1–6 years) was compared with a fibre-free sip feed in 60 children with chronic illness. The subjects either received a trial sip feed containing 150 kcal (100 ml)−1 and 2.0 g (100 ml)−1 of fibre or a fibre-free equivalent control sip feed for 12 weeks. Blood biochemistry, haematology, anthropometry, tolerance and food intake data were estimated during week 1 and 12. The fibre intake was higher (P < 0.0001) and laxative usage decreased in the fibre-containing sip feed group. The sip feed provided almost 50% of fibre intake in the trial group. There were no differences in sip feed tolerance, anthropometry, nutritional biochemistry or haematology between the two groups. Sip feeds provide an important source of fibre for sick children with normal gut function requiring nutritional support.