Point-of-care ultrasound (POCUS) can be used to guide the resuscitation of patients in cardiac arrest, septic shock, and undifferentiated shock. In cardiac arrest, POCUS can diagnose arrest etiology, guide treatment, recognize return of spontaneous circulation, and assess prognosis. In undifferentiated shock, POCUS can assess hemodynamics and modify treatment strategies. In sepsis and septic shock, POCUS can identify the source of the infection, guide treatment, optimize hemodynamics, and monitor response to treatment. Resuscitative ultrasound can be used to enhance the care of critically ill patients.