Hygiene and preventive medicine. The branch of medical science concerned with the prevention of disease and with promotion of physical and mental health, through study of the etiology and epidemiology of disease processes. The learned profession that is mastered by graduate training in a medical school and that is devoted to preventing or alleviating or curing diseases. Environmental medicine is a multidisciplinary field involving medicine, environmental science, is concerned with the interaction between mankind and the environment, is overlapping with environmental pathology. I am sure that this book needed to our students from Asia, Africa and Latin America to better understand the basic tasks that stand in front of Preventive Medicine and the ways of solving the ecological and hygienic problems, to improve the health of the populations in their countries. Professor A1 Sabounchi A.A.