Summary : With even more advances in molecular biology and immunology, scientists and farmers alike will be able to improve plant disease diagnosis. Efforts are already underway to produce better diagnostic kits to detect pathogens in crops important to developing countries. For instance, the Department of Biotechnology of India's Ministry of Science and Technology is developing diagnostic kits to detect viruses in fruits, ornamentals, spices and plantation crops. The Genetic Engineering Services Unit of Egypt's Agricultural Genetic Engineering Research Institute has developed diagnostic kits and testing services to detect viruses in crop plants. Diagnostic kits are an investment: they may be expensive, but the costs can be offset by gains, such as reduced crop losses and more environment-friendly crop management practices. their development should be made a priority by both the public and private sectors in developing countries.