Working in a field hospital after manmade or nature disasters is a demanding mission, known to cause various physical and mental bad outcomes, from depression to post-traumatic stress disorder. The mental health professional (MHP) is critical for every field hospital and humanitarian missions. At the immediate aftermath of the trauma, his or her main mission is to help the other teams to cope with the sights and difficult decision making and, in later stages, the role is enlarged to helping the coping of disaster casualties as well as community leaders. The MHP’s part starts prior to leaving for the mission, with building the team’s resiliency, and ends weeks after coming back from the mission making sure no personnel suffers from secondary traumatization. The demands from the MHP varies when the mission is in high resources country versus low ones, with its differences on the hospital teams condition, urgency, and mental and physical load. Yet, he or she would always have a place in working with the teams during working hours and in a daily closure (through a modified debriefing), liaisons, and actual patient’s treatment, and that should be his or her main mission in field hospital activity.