Metastasis is the process by which cancer spreads to form secondary tumors at downstream locations throughout the body. This uncontrolled spreading is the leading cause of death in patients with epithelial cancers and is the main reason that suppressing and targeting cancer has proven to be so challenging. Tumor cell extravasation is one of the key steps in cancer's progression towards a metastatic state. This occurs when circulating tumor cells found within the blood stream are able to transmigrate through the endothelium lining and basement membrane of the vasculature to form metastatic tumors at secondary sites within the body. Predicting the likelihood of this occurrence in patients, or being able to determine specific markers involved in this process could lead to preventative measures targeting these types of cancer; moreover, this may lead to the discovery of novel anti-metastatic drugs. We have developed a microfluidic device that has shown the extravasation of fluorescently labeled tumor cells across an endothelial cell lined membrane coated with matrigel followed by the formation of colonies. This device provides the advantages of combining a controlled environment, mimicking that found within the body, with real-time monitoring capabilities allowing for the study of these biomarkers and cellular interactions along with other potential mechanisms involved in the process of extravasation.