Psidium guajava L., popularly known as guava, is one of the most gregarious fruit trees which belongs to the family Myrtaceae. It is considered a hardy crop which even can flourish well in neglected soils. Guava fruit acquires round, ovoid or pear-shape and transudes a strong, sweet, musky odour when ripe. Fruit is very good source of vitamins A and C. The perishable nature of guava makes it vulnerable to a range of diseases from root to crown, including fruits, due to variable climatic conditions. It is affected by bacteria, fungi, algae, nematodes, and sometimes even physiological disorders can also be the cause of different postharvest diseases (Misra, 2005). The estimated loss due to various postharvest diseases is 40%; of this, fungal pathogens are blamed for more than 30% damage during storage and transit. Alternaria sp., Aspergillus niger, Penicillium, Pestalotia psidii, Rhizopus stolonifer, Colletotrichum gloeosporioides, etc. are the fungal pathogens which infect guava after harvesting. Bacteria, nematodes, algae and some of the epiphytes also affect the harvested guava fruits substantially. Diverse approaches such as application of mild chemicals just few days before harvesting, utilization of biocontrol agents and use of essential oils of plant origin singly or in combination are in practice to save postharvest losses in guava. Many fungal pathogens predominantly reported to attack guava after harvesting still need to be studied thoroughly. In this chapter, we explore scientific communications for disease incidence and control measures adopted to manage postharvest diseases in guava.