Patients in the pediatric intensive care unit (PICU) often suffer from a variety of pathophysiologic conditions that are associated with abnormal hemostasis. Bleeding is a major complication of any surgery or trauma, thus patients with inherited or acquired coagulopathies or those experiencing massive trauma or undergoing major (especially cardiac) operations present a special challenge to the ICU experts as well as to the hematologist. Awareness of thromboembolic events in the pediatric population has been increasing in the past few years mainly due to improvement in diagnostic tools, advances in new therapy and procedures, together with an increased index of suspicion. Young infants are at greater risk for either bleeding or thromboembolic events, due to lower concentration of vitamin K-dependent procoagulant clotting factors, reduced thrombin potential, and altered fibrinolytic pathway with low levels of the coagulation inhibitors. The combination of infection, hypotension, acidosis, and release of activated substances, such as tumor necrosis factor, is common after severe trauma or in seriously ill ICU patients and often leads to disseminated intravascular coagulation, which may be complicated either by bleeding or thrombosis. The conditions, risk factors, and therapeutic options available for critically ill PICU patients are discussed in this review.