Book excerpt: This book provides a practical guide to the commonly used detection methods for seed-transmitted viruses and viroids affecting both tropical and non-tropical crops. The first part describes important aspects of seed-transmitted viral diseases. The second and main part contains principles of the detection techniques and step-by-step protocols accompanied by method optimization and comments. Most of the described techniques can be equally applied to plant viruses and viroids other than seedborne ones. This book will be of significant interest to those working in seed testing laboratories and students and teachers within plant pathology and seed science.