Background: The role of metastatic site in MCCID is unclear. The goal of this study is to evaluate if metastatic site influence survival in this setting of patients (P). Methods: Analyses were based on individual data of 300 P with MCCID treated with biochemical modulation of 5- Fluorouracil by Methotrexate regimens in different prospective trials conducted at GOCS Institutions since May 1984 to Aug 2000. P with surgical resection of liver metastases were not included in the analyses. 38 P were excluded for incomplete data. P were grouped according to metastatic sites into group A= Liver metastases only (n=161), group B= Liver and other metastatic sites (n=61) and group C= Non liver metastases (n=40) (lung, peritoneal, others). Different prognostic variables were considered: age, sex, PS, weight loss, size of liver metastases, unilateral or bilateral liver involvement, number of liver metastases, histologic differentiation of primary tumor, location of primary tumor, lactate dehydrogenase, alkaline phosphatase, ALT, AST and hemoglobin. Overall survival (OS) was analyzed since date of diagnosis by means of Kaplan-Meier and the Log-rank test was used to assess the differences. Results: The average follow-up time was 14.4 months (0–73.4). Clinical, laboratory and tumor characteristics were similar among groups A, B and C respectively. However P in group A had bigger size of liver metastases, higher number of them and more bilateral liver involvement respect to group B (p=0.02, p=0.03, p=0.05 respectively). Median OS in group A=21.0 months, group B=13.1 months and group C=15 months (p= 0.02). Statistical difference in OS was observed between group A and group B (p= 0.015). No difference was observed between groups A plus B vs the heterogeneous group C (p= 0.83) Conclusions: P with liver only metastatic site had better prognosis respect to those with other coexisting site of metastases despite presenting higher tumor burden in the liver. No factors analysed in the study explaine this difference. The subset of P with liver only metastatic site would be considered as a distinctive group and deserve further molecular studies.