Venous thrombosis is a common disease process leading to tens of thousands of deaths per year. Despite prophylactic efforts, venous thromboembolic disease is a common and serious complication in critical care patients. Difficulty and delay in obtaining diagnostic imaging studies to rule out deep venous thrombosis is exacerbated by increased susceptibility that critically ill patients have to thromboembolism. Lower extremity venous ultrasound use by clinicians has been well studied and has proven both reliable and efficient. Evaluation of the upper extremities can be more challenging and requires a higher degree of technical skill. However, both can be integrated into an overall scheme of prevention, screening, and rapid diagnosis of thromboembolic disease and its complications. This article delves into available literature and describes performance of both applications in a critical care setting.