Forest protection is a practice of preventing and controlling both biotic and abiotic agents, which affect forests and their associated products. There are two agents responsible for tree injury and diseases namely non-pathogenic and pathogenic, they are also known as abiotic and biotic respectively. Non-pathogenic agents include fire, climatic conditions (e.g. wind, drought, rain, and heat), soil conditions and air pollutants. Pathogenic agents cause diseases and they include viruses, bacteria, fungi, mycoplasmas (e.g. protozoa and algae); parasitic plants (e.g. mistletoes), nematodes, arthropods (e.g. insects), birds and mammals. Forest fire, pathology and entomology are discussed in detail in this chapter.