Mosaic symptoms in sugarcane are associated with four diseases that are caused by several viruses: mild mosaic caused by the Sugarcane mild mosaic virus (SCMMV), mosaic caused by the Sugarcane mosaic virus (SCMV) and the Sorghum mosaic virus (SrMV), streak mosaic caused by the Sugarcane streak mosaic virus (SCSMV) and striate mosaic caused by the Sugarcane striate mosaic-associated virus (SCSMaV). Among those, mosaic is the most known and world wide spread disease. A number of techniques based on the detection of virus nucleic acids are available for diagnosis of sugarcane mosaic diseases. Several reverse-transcription polymerase chain reaction (RT-PCR) protocols were developed for molecular diagnosis of SCMV, SrMV, SCSMV and SCSMaV. These protocols are generally based on the virus coat protein sequence. Because this sequence is often variable, the effectiveness of the RT-PCR assays to diagnose all isolates/strains of the pathogen needs to be tested. No molecular assay is yet available to diagnose SCMMV.