Objective: To evaluate the effects of early postoperative enteral nutrition (EEN) and total parenteral nutrition (TPN) on immune system and inflammatory responses of gastrointestinal neoplasm patients undergoing major abdominal surgery. Methods: Forty-six patients undergoing gastrointestinal neoplasm radical surgery from October 2001 to March 2003 were studied prospectively. They were randomly divided into two groups: EEN + PN group (22 patients) and TPN group (24 patients). The nutritional support was started within the first 24 hours postoperatively with isocaloric and isonitrogenous regime. Immune and inflammatory responses parameters were measured before operation and at the postoperative intervals. Results: T-lymphocyte subsets maintained stable in EEN + PN group, and decreased in TPN group. CD3, CD4, and IgM in EEN + PN group were significantly higher than those in TPN group on the 7th day after operation (P < 0.05). The level of interleukin2 (IL2) in TPN group was significantly higher than that in EEN + PN group on the 1st day after operation (P < 0.05). No significant differences were found between the two groups in C-reactive protein, tumor necrosis factor-α, CD8, CD4/ CD8, IgA, and IgG before operation and on the 1st, 3rd, and 7th day postoperatively (P > 0.05). Conclusion: EEN + PN improves immune respon ses and may be the first choice for nutritional support in patients undergoing gastrointestinal surgery.