Despite several decades of world-wide research in chemotherapy and nanotherapy against solid tumors and metastases, poor delivery of drugs to the targeted site and failure of the drug to accumulate in the targeted tissue remain serious road blocks. In this chapter, magnetic targeting as an innovative approach to enhance the concentration of magnetic nanoformulations in tumor tissue is discussed, together with noninvasive imaging techniques, with special emphasis on Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and Magnetic Resonance Imaging. Magnetic Targeting of tumors has to compete with external barriers, en-route barriers, and cellular barriers to drug delivery, as well as corona formation. Novel research has clearly indicated that magnetic targeting can be combined with active targeting approaches, leading to maximal concentration enhancement of magnetic nanoformulations in tumor tissue and subsequent cellular uptake. Enhanced drug transport and retention has also led to significantly improved treatment outcomes in mouse models. © The Royal Society of Chemistry 2017.