In 1970, under the sponsorship of Oak Ridge Associated Univer­ sities (ORAU), a group of clinical investigators formed the Cooper­ ative Group to Study Localization of Radiopharmaceuticals. The first radiopharmaceutical selected for study was 67-Gallium (67-Ga) administered as the citrate. The object of the study was to de­ termine the usefulness of 67-Ga in the diagnosis and treatment of patients with various malignancies. Funding for the project was granted by the U. S. Atomic Energy Commission and the National Cancer Institute, National Institutes of Health (NIH). The Nuclear Medicine Department of the Clinical Center, NIH, agreed to assist ORAU with aspects of this study, particularly with 67-Ga scin­ tigraphy of patients with lymphoma and Hodgkin's disease. Pre­ liminary reports from the ORAU study are in press. Since April 1971, 67-Ga scintigraphy has gained increasing use in the study of cancer patients at the Clinical Center, NIH, where well over 1000 such patients have been examined by this method. This monograph was written to present selected examples from this group of a variety of malignancies seen in this 28-month period. No attempt has been made to correlate this overall experience statistically. Rather, this presentation is to help familiarize the practitioner of Nuclear Medicine with the wide range of usefulness for 67-Ga scintigraphy while making him aware of the variation in scan appearance and watchful of the many pitfalls of 67-Ga scan interpretation. Permission to use these patient studies and x-rays was generously granted by Dr. Paul P. Read Less