Systemic inflammation as evidenced by the Glasgow prognostic score (GPS) predicts cancer-specific survival in various types of cancer. The aim of this study was to evaluate the significance of GPS in patients with both synchronous and metachronous unresectable colorectal cancer liver metastases (CRLM). The subjects were 40 patients who were diagnosed as having unresectable CRLM between March 2000 and August 2010 at Jikei University Hospital. For the assessment of systemic inflammatory response using the GPS, the patients were classified into three groups: patients with normal albumin (≥3.5 g/dl) and normal CRP (≤1.0 mg/dl) as GPS 0 (n=27), those with low albumin (<3.5 g/dl) or elevated CRP (>1.0 mg/dl) as GPS 1 (n=6), and both low albumin (<3.5 g/dl) and elevated CRP (>1.0 mg/dl) as GPS 2 (n=7). We retrospectively investigated the relationship between patient characteristics including GPS and survival using univariate and multivariate analyses. Results of the univariate analysis revealed that absence of primary tumor resection (p=0.0161), absence of systemic chemotherapy (p=0.0119), serum carcinoembroynic antigen (CEA) of ≥100 ng/ml (p=0.0148), serum carbohydrate antigen (CA)19-9 of ≥100 U/ml (p<0.0001) and GPS 2 (p=0.0362) were significant predictors of poor survival. Results of the multivariate analysis revealed that serum CEA of ≥100 ng/ml (p=0.0015), CA19-9 of ≥100 U/ml (p<0.0001) and GPS 2 (p=0.0042) were independent predictors. In conclusion, GPS at diagnosis of unresectable CRLM is an independent prognostic predictor of overall survival.