Intercellular adhesion molecule 1 (ICAM-1), also known as CD54, is a nearly ubiquitous transmembrane glycoprotein that is normally expressed in endothelial and immune cells and has a key role in leukocyte migration and activation. It binds to CD11a/CD18 or CD11b/CD18 type integrins and is also utilized by rhinoviruses as a receptor. Soluble intercellular adhesion molecule 1 (sICAM-1) promotes angiogenesis and can be used as an indicator of activated or damaged vascular endothelial cells. It also acts as a transmembrane ICAM-1 inhibitor, mediating activities such as monocyte adhesion to activated endothelial cells and sensitivity of tumor cells to NK cell-mediated lysis. Monitoring serum levels of sICAM-1 expression may provide a more detailed perspective on a variety of pathologies such as cardiovascular disease, type II diabetes, organ transplantation disorders, oxidative stress, abdominal cellulite, hypertension, liver disease, and certain malignancies.