Severe undernutrition nearly always leads to marked changes in body spaces (e.g., alterations of intra-extracellular water) and in body masses and composition (e.g., overall and compartmental stores of phosphate, potassium, and magnesium). In patients with severe undernutrition it is almost always necessary to use oral nutrition support and/or artificial nutrition, besides ordinary food; enteral nutrition should be a preferred route of feeding if there is a functional accessible gastrointestinal tract. Refeeding of severely malnourished patients represents two very complex and conflicting tasks: (1) to avoid “refeeding syndrome” caused by a too fast correction of malnutrition; (2) to avoid “underfeeding” caused by a too cautious rate of refeeding. The aim of this paper is to discuss the modality of refeeding severely underfed patients and to present our experience with the use of enteral tube feeding for gradual correction of very severe undernutrition whilst avoiding refeeding syndrome, in 10 patients aged 22 ± 11.4 years and with mean initial body mass index (BMI) of 11.2 ± 0.7 kg/m 2. The mean BMI increased from 11.2 ± 0.7 kg/m 2 to 17.3 ± 1.6 kg/m 2 and the mean body weight from 27.9 ± 3.3 to 43.0 ± 5.7 kg after 90 days of intensive in-patient treatment ( p < 0.0001). Caloric intake levels were established after measuring resting energy expenditure by indirect calorimetry, and nutritional support was performed with enteral feeding. Vitamins, phosphate, and potassium supplements were administered during refeeding. All patients achieved a significant modification of BMI; none developed refeeding syndrome. In conclusion, our findings show that, even in cases of extreme undernutrition, enteral feeding may be a well-tolerated way of feeding.