Effect of the ionizing radiations in the Conservation of the Guava (Psidium guava-L) in fresh as treatment post-crop. The food radiations is a physical process of conservation, that has for object to prolong the useful life of the products nutritious treaties, maintaining in appropriate form the nutritional characteristics and organoleptic. The ionization treatment consists on irradiation of high constituted energy of photons or quick electrons. The main types of rays used in the ionization treatment are: the photons, the quick electrons and the photons x. The center of gamma radiation has as energy source a cylinder of Co-60 that it diffuses rays gamma in the space and it irradiates the products. The irradiation of any aliment until a dose of 10 kGy, it doesn't present any toxicological risk and it doesn't introduce difficulties of nutritional or biological order. The IAEA has as primordial mission; the to hurry and to increase the peace and the prosperity in the whole world. The common guava is a fruit it would originate of tropical America, it is in the tropics and subtropics and it is of commercial importance in the national and international environment.