The environment of a field hospital is just a compromise between hygienic needs of a hospital and the surroundings in the field. Especially if patients are in bad conditions and their immune system doesn`t work well, they are not able to stand any pathogenic microorganism. Based on the model of the Red Cross field hospital this work gives attention to the hygiene part in such a field hospital and describes water purification and sanitation to handle the bad hygiene conditions. This thesis also deals with different, new and old, types of water purification and latrines and gives a short summary about advantages and disadvantages of each type. At least the most important thing is, that everybody knows, he is a part of functional hygiene and everybody has to do the best, to save himself and everybody else from infections. For this last part, there is a short introduction about all-purpose personal hygiene.