Nuclear oncolgy is important in the diagnosis, staging, and long-term surveillance of a number of cancers. Over the past 10 years there has been an explosion of new radioisotopic tracers aimed at detecting, staging and eventually treating tumors. Clinicians and oncologists can now use specific radiolabeled metabolic tracers, monoclonal antibodies, and molecular probes based on the sequencing of the human genome. The current applications of positron emission tomography (PET) in oncology have included characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. Radioimmunoscintigraphy is a technique which uses radiolabeled antibodies to visualize tumors, taking advantage of antigens preferentially expressed by malignant tissue. However, the implementation of radiolabeled antibodies as "magic bullets" for detection and treatment of diseases such as cancer has required addressing several shortcomings of murine monoclonal antibodies. Genetic engineering provides a powerful approach for redesigning antibodies for use in oncologic applications in vivo. Recently, noninvasive molecular imaging has been developed. Most current molecular imaging strategies are "indirect" and involve the coupling of a "reporter gene" with a complementary "reporter probe". Imaging the level of probe accumulation provides indirect information related to the level of reporter gene expression. In this article, the author discuss the current status of PET, radioimmunoscintigraphy, gene imaging and receptor imaging with a brief review on nuclear oncology.