For a number of developing countries, cereals and grain legumes represent the basic element of the population's diet, especially for the lowest-income, generally rural, groups. In these countries, food self-sufficiency still remains an unachieved objective, and this is not always or only because of the inefficiency of the local production systems. The extent of post-harvest losses sometimes seriously limits the impact of the efforts made to increase food production; such losses decrease local availability of food, forcing national policy-makers to resort to massive imports of foodstuffs, thereby increasing their food dependency. The governments of developing countries, as well as a number of NGOs, bilateral and multilateral international cooperation agencies, and especially FAO, have been engaged for several years in projects aimed at the prevention of food losses. The experience acquired during these interventions has often demonstrated the need not only for improving production methods but also for making both farmers and concerned institutions aware of the problem of post-harvest losses. This publication is primarily addressed to members of the technical or administrative staffs of government services or assistance to development agencies working in field projects related to prevention of grain losses. It is a manual of basic information on post-harvest operations concerned with the principal foodstuffs of the developing countries: rice, maize, sorghum, beans, groundnut and sunflowers. As such, it will be useful to field staff (extension agents, rural leaders, development agents) who are participating in the implementation of projects aimed at improving post-harvest operations.