The tsunami that struck Southeast Asia on December 26, 2004, resulted in the deaths of >300,000 individuals. The U.S. response included the formation of the first combined civilian/ military peacetime humanitarian effort, directed by the National Command Authority as Operation Unified Assistance. This effort included military personnel from the U.S. Navy and civilians assembled by Project HOPE. Anesthesiologists and certified nurse anesthetists provided care in >150 cases. We discuss the initial response, medical and cultural planning, logistical support, procedures, and lessons learned in this unique opportunity.