We have used PCR simultaneously detect multiple viruses in a single PCR assay. Briefly, co-amplification was performed with primers derived from the gag region of HIV-1 (SK 38/39) and the LTR region of HIV-2 (SK 89/90), HIV-1 and HCV (hepatitis C virus) and reaction. Amplification was performed with primer pairs specific for a set of 2 of these viruses (HIV- 1/HIV-2, HIV-1/HCV, HIV-1/HBV) and the products analyzed by hybridization with virus-specific probes. Fewer than 10 copies of each viral DNA could be detected by this method. This assay was used to detect the respective viruses in co-infected clinical samples. Abstracts describing this work will be presented at the International Congress of Virology, Berlin, Germany and the meeting on Liver Diseases. A manuscript has been submitted to the Journal of Clinical Microbiology and another manuscript is in preparation.