28 malnourished patients with Crohn's disease completed a controlled cross-over study to examine the effect of a low-residue liquid supplement on nutrition and disease activity. Patients spent two months on an ordinary diet (control period) and for two months took the nutritional supplement in addition (treatment period): the order of treatment and control periods was randomised. All anthropometric measurements, serum proteins, creatinine height index, and circulating T lymphocyte numbers increased significantly in the treatment period, while serum orosomucoid levels dropped significantly, suggesting that disease activity was reduced. The benefits were apparently due to the higher calorie intake with the enteral supplement. The results show that enteral supplementation can be managed successfully at home and may produce improvements in nutrition and disease activity.