Aminopeptidase N (APN/CD13) of the M1 family is a broad specificity enzyme that is intimately involved in tumor angiogenesis and metastasis. Asparagine–glycine–arginine (NGR) is a tumor-homing tripeptide, which can selectively combine with APN/CD13 that is overexpressed on the surface of some tumor cells. Various anti-tumor drugs can be conjugated to NGR to improve selectivity, efficacy, and to decrease drug toxicity. In this study, a tripeptide NGR(NO2) was synthesized and conjugated with 5-fluorouracil. The anti-tumor activities of this new prodrug were evaluated in vivo. More significant anti-tumor effects were observed over the parent 5-fluorouracil.