Abstract: The merging of molecular biology and nuclear medicine is developed into molecular nuclear medicine.Positron emission tomography (PET) of gene expression in molecular nuclear medicine has become an attractive area. Positron emission tomography imaging gene expression includes the antisense PET imaging and the reporte gene PET imaging. It is likely that the antisense PET imaging will lag behind the reporte rgene PET imaging because of the numerous issues that have not yet to be resolved with this approach. The reporter gene PET imaging has wide application into animal experimental research and human applications of this approach will likely be reported soon.