The Radiation Safety Officer (RSO) is responsible for the safety of the staff, visitors, and patients who may work with, or come into contact with, radioactive materials. This responsibility often calls for establishing and enforcing radiation safety policies and procedures. The position of the RSO may have even greater dimensions at facilities where medical research uses radioactive materials or where radioactive sources are being implanted in cancer patients for therapy. Since the nuclear pharmacist handles radioactive solids, liquids, and/or gases on a daily basis, his knowledge and experience ideally qualify him to perform the duties of an RSO. Those duties and responsibilities include, but are not limited to, monitoring for environmental safety and personnel radiation exposure, monitoring of incoming and outgoing radioactive shipments, and verification that all record-keeping activities, possession quantities, and uses of radioactive material are in keeping with the facility's radioactive material license. Basically, the RSO is responsible for the safe use of any radioactive material from the time it arrives until the time it is removed for waste disposal. The following article reviews some of the duties of the RSO, and shows how easily the nuclear pharmacist can assume this role.