Objective: This study aimed to clarify the relationship between host nutritional status prior to first-line chemotherapy and therapeutic effect, and, whether these nourishment indexes could become factors that predict long-term convalescence in unresectable advanced or recurrent colorectal cancer or not. Summary of Background Date: It has previously been reported that postoperative complications and long-term prognosis of patients with gastrointestinal malignancies may be affected by their nutritional status. But, there is little information regarding the relationship between prognosis, nutritional status and immunocompetence in unresectable progressive or recurrent colorectal cancer.Methods: Ninety patients who had measurable target lesions underwent resection for primary colorectal cancer in our institution, between April 2007 and March 2013. The indicators of host nutritional status was body weight (BW), body mass index (BMI), serum albumin, Onodera's prognostic nutritional index (OPNI) and Glasgow Prognostic Score (GPS). The indicators of host immunocompetence was total lymphocyte counts, total neutrophil counts, granulocytes/lymphocytes ratio (G/L ratio). Results: The median overall survival (OS) was 32.5 months, and the median progression-free survival was 10.9 months. The relative change of target lesions were associated with BW, BMI and OPNI. Furthermore, there was strong correlation between the change ratio of the serum CEA level before and after chemotherapy administration and BMI. BW, BMI, serum albumin level, OPNI and GPS were significantly associated with overall survival (OS). Conclusion: Poor nutritional status and suppressive immunocompetence is associated with ineffective chemotherapy.