Horticultural crops are known for their high return per unit time and area. How ever, a significant proportion of postharvest loss of these produces is experienced in Ethiopia. This postharvest loss contributes to the reduction of profit from the produce and leads to food insecurity. This survey investigation and laboratory analysis was therefore conducted to study the causes and magnitude of post harvest loss of selected fruits in three different towns of Jimma Zone, South western Ethiopia from November 2010 to March 2011. The survey method was explored using carefully designed semi-structured questionnaire reflecting the proposed scope of study among producers, wholesalers and retailers of fruits in the fruit market chain. The chemical analysis was determined using the standard procedures in Postharvest laboratory of Jimma University College of Agriculture and Veterinary Medicine. The result indicated that there were greater postharvest losses of mango (35.5%) and banana (40.0%) especially in Jimma town than in Agaro and Seka Chekorsa. These postharvest losses were mainly attributed to poor handling during transportation and the use of poor marketing structures to sell their fruits. To reduce the losses of these fruits, it calls for a close integration of the beneficiaries along the value chain and a public awareness campaigns to increase their experience of using appropriate packing materials.