For ensuring success of gene and cell based therapies it is of prime importance to develop technology for non-invasive monitoring of the location and duration of gene expression, distribution and targeting of therapeutically engineered cells and vector particles in vivo. A number of advances have been achieved in high resolution, in vivo imaging methods, such as bioluminescence imaging, Magnetic resonance imaging (MRI), positron emission tomography (PET) and various fluorescence imaging techniques, including fluorescence mediated tomography (FMT) and near infrared fluorescence (NIRF) reflectance imaging. In this review we will discuss different imaging modalities that have found applications in gene and cell therapies of cancer.