Objective: To investigate the effect of growth hormone(GH) and hypo calorie enteral nutrition(EN) on protein metabolism in patients after cardiac operations. Methods: 36 patients after cardiac operations were randomly divided into two groups. The test group received GH and EN, and the control group received EN only. The treatment was maintained 7 days postoperatively. Plasma albumin(A)?transferrin(TF)?prealbumin (PA)?retinol binding protein(RBP) on the preoperative day and day 1,4,8 postoperatively and nitrogen balance(NB) on the day 1,2,3,5,7 postoperatively were detected. Results: There was no significant difference of all plasma protein levels between two groups before operation and all decreased on the 1st postoperative day, but only RBP higher in the test group than that in the control. There was significant difference in TF,PA,RBP levels on the 4th and 8th postoperative day, the plasma A level on the 8th postoperative day, and NB on the 1st to 7th postoperative day between the two groups. Conclusion: Combined use of GH and EN can elevate plasma A,TF,PA,RBP levels and improve negative NB.