This review traces developments in plant virus research from its very beginning in the eighties of the 19th century until the present day. Starting with the earliest research, which gave a clue as to the existence of a pathogen different from the then known bacteria and fungi, the subsequent topics in plant virus research are highlighted, including the spread of plant viruses in nature and their relationships with possible vectors. In the course of more than a century, macroscopical and (sub)microscopical studies gave way to those with a molecular dimension, thanks to the development of sophisticated molecular-biological techniques and information technology. As a result an insight has been gained into both the molecular characteristics of plant viruses and various resistance mechanisms in plants.