Objective: To investigate the effects of the combination of imbalanced branched-chain amino acids and 5-fluorouracil (5-FU) on nutritional and survival condition of tumor-bearing rats. Methods: The SD rats were each given a catheterization of jejunostomy and an inoculation of Walker-256 carcinosarcoma cells subcutaneously. Forty-eight rats were randomized into 4 groups: Group A (balance amino acid + NS), Group B (balance amino acid + 5-FU), Group C (valine-depleted amino acid + 5-FU), and Group D (complex amino acid of valine-depleted and leucine-supplemented + 5-FU). The change of rat′s weight, main organ weights, serum prealbumin (PA) and transferrin (TF) concentration were investigated.In addition, rat′s survival time was observed. Results: The loss of rat′s weight in group C was significantly increased compared with group A and B (P