Development of an in vitro model for the early stages of cardiovascular disease is a current necessity. Cardiovascular disease is the leading cause of death in the United States and throughout the world. Oxidative stress and reactive oxygen species have been implicated in cardiovascular disease development. An in vitro model of these processes will improve our understanding of cardiovascular disease development and allow for the development of additional treatments. Atherosclerosis is an inflammatory disease and increased levels of H 2 O 2 are associated with inflammation. The model focuses on H 2 O 2-induced oxidative stress under static and shear conditions. Previous studies have documented increased O 2 .and increased cytotoxicity in smooth muscle cells exposed to H 2 O 2. Under static culture, endothelial cells exposed to H 2 O 2 , exhibited increased O 2 .over basal levels via NOS and NAPDH oxidase pathways. Increased O 2 .was attenuated by MnSOD adenoviral-mediated upregulation and endothelial cell exposure to Tiron. This suggests NOS and NADPH oxidase as sources of increased O 2 .under H 2 O 2-induced oxidative stress. Endothelial cell cytotoxicity was increased with H 2 O 2 exposure. The increase in cytotoxicity was diminished upon exposure to Tiron or L-NAME. Under shear conditions (8.2 dynes/cm 2), endothelial cells exposed to H 2 O 2 exhibited increased O 2 .compared to control via an L-NAME (specific inhibitor NOS) and Apocynin (NADPH oxidase inhibitor) inhibitable mechanism. This suggests NOS and NADPH oxidase as sources of increased O 2 .under H 2 O 2-induced oxidative stress. The increased O 2 .was attenuated with MnSOD adenoviral-mediated upregulation and endothelial cell exposure to Tiron (an O 2 .scavenger). Endothelial cell attachment under shear with exposure to H 2 O 2 was improved with MnSOD adenoviral-mediated upregulation as observed by decreased loss of the endothelial cell monolayer compared with H 2 O 2 exposed endothelial cells.