From the review of published data and our own experience the following conclusions appear pertinent. In the limited number of well-controlled studies available for evaluation, a significant reduction in the transmission of clinically apparent hepatitis has been demonstrated following the exclusive administration of frozen blood. There is no uniform method of frozen blood treatment by current application and the strong possibility exists that as far as the removal of Hepatitis Type B virus. One method may be more effective than another. The transmission of hepatitis by blood administration represents only one of a number of potential modes of spread in a dialysis population. The prevention of serious epidemics whithin these patient populations will be accomplished only with careful attention to all facets of cross contamination. Because of multiple potential sources of spread within the hemodialysis population, these groups of individuals probably represent a poor choice of subjects in which we can effectively evaluate transmission by a single factor, such as frozen-thawed erythrocytes. Until the advent of better methods of prevention, efforts toward prevention and limitation must be multifocal and that should include the use of frozen-thawed erythrocytes.