Abstract Angiogenic blood vessels found within growing tumors express high levels of integrin ανβ3 while mature vessels fail to express this integrin. Based on this we developed a ανβ3-targeted nanoparticle (NP) in an attempt to selectively deliver therapeutics to the tumor neovasculature. A cyclic peptide ligand (cRGDfK) coupled to a phospholipid and incorporated into a nanoparticle demonstrated specific binding to ανβ3 on cultured endothelial cells. To characterize the in vivo targeting capacity of these NPs, we monitored NP accumulation using intravital microscopy of tumor neovasculature. A dorsal skin-fold window chamber implanted with GFP-labeled melanoma cells lacking integrin ανβ3 were imaged at various times after NP injection into the bloodstream. By 5h post injection, the cRGDfK NPs targeted the neovasculature at the angiogenic tips adjacent to the tumor margin, whereas untargeted (cRADfK) NPs failed to bind. After establishing in vivo targeting, these ανβ3-targeted NPs were loaded with doxorubicin via an ammonium phosphate gradient for therapeutic studies. The cRGD-Dox particles disrupted angiogenesis in the mouse matrigel model leaving only small fragments of disrupted vessels within the FGF loaded plugs. Next, we utilized an orthotopic pancreatic cancer model to study the ability of the NPs to target the vasculature of both primary pancreatic tumors as well as metastatic sites including the hepatic hilar lymph node and mesenteric lymph nodes. cRGD-Dox particles injected systemically at 1 mg/kg produced a profound anti-metastatic effect while only marginally influencing the pre-established primary tumor within the pancreas. This is much improved compared to the free doxorubicin treatments in which 1 mg/kg of free doxorubicin had no effect and 15 mg/kg of free doxorubicin was required for a similar therapeutic effect in this orthotopic model. Animals treated with 15 mg/kg of free doxorubicin lost over 20% of their body weight within 7 days, whereas no decrease in body weight was observed in the cRGD-Dox treated animals, confirming the reduction in overall toxicity. Histology confirmed that the cRGD-Dox particles induced apoptosis in regions co-localized with β3 expressing tumor vasculature. Additionally, we tested the cRGD-Dox particles in an orthotopic renal cell carcinoma model. Similar to the pancreatic carcinoma, the cRGD-Dox particles had a slight effect on primary tumor growth but greatly reduced metastasis to several sites including the pancreas, liver, spleen, and diaphragm. These findings reveal that ανβ3 targeted NP drug delivery may preferentially disrupt newly forming metastatic lesions by delivery of chemotherapeutic agents to sites of active angiogenesis in which the endothelium expresses high levels of ανβ3.