The effects of LCT-based lipid emulsions used in TPN on immune system remains controversial. In this prospective study we research the effects of three types of TPN on T-lymphocyte subsets and NK cells. 21 patients diagnosed because of upper gastrointestinal carcinoma (UGIC), and amenable of curative surgery were included in the study. TPN support was maintained 10 postoperative days at least. All patients received 35 non-proteic Kcal/KG BW/day. Group I (without lipid): received 100% of caloric intake (CI) by glucose. Group II (LCT): received 55% of CI by glucose and 45% by LCT at 20% emulsion. Group III (MCT/LCT): received 55% of CI by glucose and 45% by MCT/LCT at 20% mixture. T-lymphocyte subsets were determined by flow cytometry preoperatively and in first and tenth postoperative days. Our results suggest that patients diagnosed of UGIC present alterations of cellular immunity. These alterations are increased by the age and by surgical act. The changes found are independent of the type of TPN. LCT-based emulsions have similar effects on T-lymphocyte subsets that MCT/LCT-based emulsions.