Initial efforts were restricted to ABO blood group systems, but there was potential for applying the technique to other antigen systems, with the possibility of making all antigen determinations simultaneously. Some success was achieved with the development of a scheme for labeling different antibodies, preparing and collecting aged bloodstains on various substrates, purifying antisera, and labeling antibodies. Although early tests with fresh blood indicated a measure of success, typing of dried bloodstains failed. Limited analysis of dificulties encountered confirmed previous researchers' difficulties with immunofluorescence techniques in typing dried bloodstains. Previous researchers believed that failure was due to impurities in the antisera. Apparently this aspect of the problem was eliminated by antisera purification, but the true causes for failure remain unresolved. The researchers still believe that the concept outlined has potential for typing antigens in dried bloodstains. Nine references are listed.