Abstract Background: 5-Fluorouracil (5-FU) is a useful chemotherapeutic agent in the treatment of solid tumors. However, it is very short half-life in plasma circulation greatly limited the in vivo antitumor efficacy, and intravenous 5FU injection is unlikely to achieve optimal dose effectiveness within peritoneal cavity. Conjugated linoleic acid-coupled Pluronic F127 (Plu-CLA) is an effective drug delivery system with numerous advantages and has an anticancer activity. It was also shown that paclitaxel loaded in Plu-CLA demonstrated synergistic tumor suppression through robust cell cycle arrest and enhanced apoptosis in tumor compared to paclitaxel in poloxamer hydrogel. The aim of this work is to evaluate the therapeutic efficacy of Plu-CLA as a new intraperitoneal 5FU delivery system. Methods: Cytotoxicity was evaluated by using CT-26 murine colon carcinoma cell. We established peritoneal metastasis models and hepatic metastasis models for colon cancer using BALB/c mice and firefly luciferase-expressing CT-26 (CT26/Fluc) cells. Tumor progression and response to therapy were monitored by bioluminescence imaging (BLI). Results: MTT assay indicated that 5-FU loaded in Plu-CLA hydrogel (P-FU) could increase the cytotoxic activity of 5-FU in CT-26. P-FU significantly enhanced apoptosis compared with 5-FU control. It was found that Caspase 3 and p21 were up-regulated, whereas Bcl-2 was down-regulated. Moreover, growth of hepatic metastases in vivo was significantly reduced in mice treated with P-FU. Treatment with P-FU substantially delayed tumor growth of intraperitoneal metastasis greatly and tumor-bearing mice treated with P-FU showed a better survival tendency than the 5-FU alone. Conclusion: These results were attributed to the synergistic effect of Plu-CLA. 5-FU administered in Plu-CLA hydrogel led to significant enhancement of tumor growth suppression and cellular apoptosis. Therefore, Plu-CLA could be a potential intraperitoneal carrier for hydrophilic 5-FU for the effective treatment of metastatic colon cancer. . Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3682.