Every year, 31,230 men and women are diagnosed with colorectal carcinoma, and up to 60% of these will ultimately develop advanced disease. However, there is little information to identify which patients are most likely to benefit from palliative chemotherapy. This analysis is unique in evaluating how the site of metastasis influences response and survival. A database of 497 patients treated within randomized clinical trials using 5-Fluorouracil (5FU)-based chemotherapy at the Royal Marsden Hospital was analysed. The potential for site of metastasis as a predictive variable for response to chemotherapy and survival was examined, in addition to other clinical parameters. The presence of liver metastases was a better predictor for overall response than either performance status or number of metastatic sites on presentation. Probability of response was significantly decreased by a raised serum carcinoembryonic antigen (CEA) and presence of peritoneal metastases. In liver metastases, a normal serum albumin was as significant a predictor for response as good performance status. The most important predictor for survival was initial performance status. The number of metastatic sites on presentation had no influence on survival. Site of metastasis can predict for response to 5FU-based chemotherapy and patients should be stratified according to the involved site of metastasis in the future.