Thirteen cultivars of hop (Humulus lupulus L.) were tested by reverse transcription-polymerase chain reaction (RT-PCR) for the presence of apple mosaic virus (ApMV). The virus was detected in various amounts in all tested cultivars. Control hop clones derived from tissue cultures, treated by thermotherapy and maintained in greenhouse were virus-free. The procedure for sample preparation and RT-PCR of ApMV is described in detail.