University of California at San Francisco: A risk assessment was made of HIV infection through prospective testing for seroconversion in women recipients of anti-HIV negative blood transfusions at the University of California San Francisco hospitals. Blood specimens were collected from each of the recipients pre-transfusion, and at two, four, and six months post-transfusion. Patients were selected based on female sex and exclusion of high risk behavior or blood transfusion during the preceding six months.