During the first year of application of seeds containing radioactive gold 198 (1–7) in clinical radiation therapy at the Ohio State University Medical Center, 100 patients were treated with the new types of gamma-ray sources. Although insufficient time has elapsed for a definitive evaluation of clinical results, it is felt that enough experience has been accumulated to warrant a review of the place of radiogold seeds in the practice of radiation therapy. No appreciable differences have been noted clinically in the reactions to therapy with radiogold, radiocobalt, radium, and radon. Radiogold seeds were found to be convenient replacements for the radon seeds formerly employed at this center. The simplicity of protection and the ease and speed of preparation of radiogold seeds of uniform strength were valuable in many situations. Whether radiogold seeds should be used in preference to needles or nylon applicators containing radiocobalt or radium will depend largely on the clinical situation. For example, in...