Since its creation in 1920, The International Mycological Institute has been concerned with the identification of plant-pathogenic fungi and bacteria. Part of its role has been the development of plant clinics, which have an important role in providing access for farmers and extension workers to specialist scientific services for the diagnosis of plant disease problems and advice on control measures. Clinics can also be bases from which surveys of crop problems are made and data on the needs of farmers are assimilated, in order to identify research priorities. This practical handbook provides information on all aspects of the technical procedures, material requirements and organisation for the effective operation of a plant clinic. It describes the diagnostic process, from field observation and collection through to methods of culture, microscopy, keeping records and reference material, general laboratory practice and equipment maintainance. The procedures described have been used successfully at IMI for many years, and through a series of training programmes, have been transferred to laboratories in many other countries. Essential reading for those involved in setting up and running plant clinics and plant quarantine facilities, this handbook will also be of interest to all practitioners and advanced students of plant pathology, particularly those concerned with diagnostics, and to crop protection specialists working in an advisory capacity.