Haptoglobin (HP) typing by vertical electrophoresis in discontinuous polyacrylamide gel was performed on 47 dog blood samples. Of these, 19 were from Doberman pinschers, 20 from German shepherds, and 8 from pit bull terriers. Conclusive results were obtained on 40 of the 47 bloods tested. Two phenotypes, a single HP banding and a doublet banding, were common in the three breeds and could not be used for differentiation between them. Although the HP typing could not distinguish between bloods from different canine species, it may be used to distinguish between canine and human bloods. Because canine HP were sufficiently different from those of humans, HP typing can be applied to determine the origin of bloodstains. 2 figures, 1 table, and 3 references (Author abstract modified)