Molecular imaging research has been focused on identification of tumor specific markers and the application of these markers for evaluation of patient response to radiation therapy, chemotherapy or chemo/radiotherapy. Though the opportunities are involved in molecule in licensing, yet, the challenges involves in regulatory compliance in investigative new drugs such as chemistry, manufacturing, control, pre-clinical pharmacology/toxicology and clinic protocol management. In this article, we reviewed the opportunities and challenges in molecular imaging using generator produced isotopes. 99mTc (technetium-99m), 68Ga (gallium-68) and 188Re (rhenium-188) are generator-produced isotopes which are readily-accessible and affordable. These generator produced isotopes were developed to label molecular targets for prediction of therapeutic response, monitoring tumor response to treatment and differential diagnosis. 188Re is a therapeutic radionuclide which can be used to target tumors and deliver lethal radiation due to high-energy β- emissions. Challenges and opportunities in molecular imaging involving drug discovery, validation, intellectual property in licensing and regulatory compliance are discussed.