Objective To compare the conjoint effect of enteral nutrition(EN) and parenteral nutrition(PN) with single EN or PN on immune function, nutritional status, complications and clinical outcomes of patients with severe traumatic brain injury(STBI). Methods A prospective randomized control trial was carried out from January 2009 to May 2012 in Neurological Intensive Care Unit(NICU). Patients of STBI who met the enrolment criteria(Glasgow Coma Scale score 6~8; Nutritional Risk Screening ≥3) were randomly divided into 3 groups and were administrated EN, PN or EN+PN treatments respectively. The indexes of nutritional status, immune function, complications and clinical outcomes were examined and compared statistically. Results There were 120 patients enrolled in the study, with 40 pationts in each group. In EN+PN group, T lymthocyte subsets CD3+%, CD4+%, ratio of CD3+/CD25+, ratio of CD4+/CD8+, the plasma levels of IgA, IgM, and Ig G at 20 days after nutritional treatment were significantly increased compared to the baseline(t=4.32-30.00, P<0.01), and they were significantly higher than those of PN group(t=2.44-14.70;P<0.05,or P<0.01) with exception of CD4+/CD8+, higher than those of EN group(t=2.49-13.31, P<0.05, or P<0.01) with exceptions of CD3+/CD25+, CD4+/CD8+, Ig G and Ig M. For the nutritional status, the serum total protein, albumin, prealbumin and hemoglobin were significantly higher in the EN(t=5.87-11.91; P<0.01) and EN+PN groups(t=6.12-13.12; P<0.01) than those in PN group after nutrition treatment. The serum prealbumin was higher in EN+PN group than that in EN group(t=2.08; P<0.05). Compared to the PN group, the complication occurrence rates of EN+PN group were significantly lower in stress ulcer(22.5% vs. 47.5%; χ~2= 8.24, P<0.01), intracranial infection(12.5% vs 32.5%;χ~2= 6.88, P<0.01) and pyemia(25.0% vs. 47.5%; χ~2= 6.57, P<0.05). Compared to the EN group, the complication occurrence rates of EN+PN group were significantly lower in aspirated pneumonia(27.5% vs. 50.0%; χ~2= 6.39, P<0.05), hypoproteinemia(17.5% vs. 55.0%; χ~2= 18.26, P<0.01) and diarrhea(20.0% vs. 60.0%; χ~2= 20.00, P<0.01). The EN+PN group also had significant less length of stay in NICU(t=2.51, 4.82; P<0.05, P<0.01), number of patients receiving assisted mechanical ventilation(χ~2= 6.08, 12.88; P<0.05, P<0.01) and its durations(t=3.41, 9.08; P<0.05, P<0.01), and the death rate(χ~2=7.50, 16.37; P<0.05, P<0.01) than those of EN or PN group.Conclusion Early EN+PN treatment could promote the recovery of the immune function, enhance nutritional status, decrease complications and improve the clinical outcomes in patients with severe traumatic brain injury. Objective To compare the conjoint effect of enteral nutrition (EN) and parenteral nutrition (PN) with single EN or PN on immune function, nutritional status, complications and clinical outcomes of patients with severe traumatic brain injury (STBI). Methods A prospective randomized control trial was carried out from January 2009 to May 2012 in Neurological Intensive Care Unit (NICU). Patients of STBI who met the enrolled criteria (Glasgow Coma Scale score 6-8; Nutritional Risk Screening ≥ 3) were randomly divided into 3 groups and were administeredrated EN, PN or EN + PN treatments respectively. The indexes of nutritional status, immune function, complications and clinical outcomes were examined and compared statistically. Results There were 120 patients enrolled in the study, with 40 sessions in each group. In EN + PN group, T lymthocyte subsets CD3 +%, CD4 +%, ratio of CD3 + / CD25 +, ratio of CD4 + / CD8 +, the plasma levels of IgA, IgM, and Ig G at 20 days after nutritional therapy were significantly increased compared to the baseline (t = 4.32-30.00, P <0.01) and they were significantly higher than those of PN group (t = 2.44-14.70; P <0.05, or P <0.01) with exception of CD4 + / CD8 + higher than those of EN group (t = 2.49-13.31, P <0.05, or P <0.01) with exceptions of CD3 + / CD25 +, CD4 + / CD8 +, Ig G and Ig M. For the nutritional status, the serum total protein, albumin , prealbumin and hemoglobin were significantly higher in the EN (t = 5.87-11.91; P <0.01) and EN + PN groups (t = 6.12-13.12; P <0.01) Compared to PN group, the complication occurrence rates of EN + PN group were significantly lower in stress ulcer (22.5% vs. 47.5%; P <0.05) (P <0.01), and Pyemia (25.0% vs. 47.5%; χ ~ 2 = 6.57, P <0.05) . Compared to the EN group, the complication occurrence rates of EN + PN group were significantly lower in aspirated pneumonia (27.5% vs. 50.0%; χ ~ 2 = 6.39, P <0.05). The incidences of diarrhea (20.0% vs. 60.0%; χ ~ 2 = 20.00, P <0.01). The EN + PN group also had significant less length of stay in NICU (t = 2.51, 4.82; P <0.05, , 12.88; P <0.05, P <0.01) and its durations (t = 3.41, 9.08; P <0.05, P <0.01) ) than those of EN or PN group. Contact Early EN + PN treatment could promote the recovery of the immune function, reinforcing nutritional status, decrease complications and improve the clinical outcomes in patients with severe traumatic brain injury.