Basic principles of oncology and their application in imaging have been mentioned. Role of FDG PET has been discussed in great detail. Also, imaging of neuroendocrine tumors using MIBG, Ga 68 DOTA TOC with illustrative images is given. Newer PET tracers like 11C choline, 18 F FET/FLT, tumor specific antibodies and monoclonal antibodies are described. Recent advances like radioimmunodetection and oligonucleotides have been mentioned.