Apple mosaic virus (ApMV) has been detected in apple and also in a number of other plant taxa including other members of the Rosaceae, hazelnut, hop, birch and a number of perennial weed species. This chapter comprehensively details how the virus is spread and describes the symptoms displayed by affected host plants. It goes on to discuss the geographical distribution of the virus, its epidemiology and the economic impact of infection on the fruit and nut industry. Ways to obtain virus-free material are reviewed with meristem culture in combination with thermo- or cryotherapy used to eradicate ApMV from propagation material. The chapter concludes with a discussion of the most reliable molecular detection methods for ApMV and a look towards future trends in ApMV research.