Serum and urine specimens were collected from volunteer donors. The serum samples were typed first for their haptoglobin (HP) phenotype determination. Each individual's corresponding urine sample of 15 milliliter was then concentrated 3000-fold by either Lyphogel beads or Centriprep-30. A final volume of 5 microliters was applied to the gradient polyacrylamide gels. Following electrophoresis, the Western blot techniques transferred HP bands from the gel to the nitrocellulose membranes, and the enzyme immunoassay with goat anti-HP antiserum and rabbit anti-goat immunoglobulin alkaline phosphatase conjugate identified the HP bands from the concentrates. Specimens stored for 6 months at -22 degrees Centigrade were also concentrated and typed successfully. This procedure allows the separation of the samples into three common phenotypes of HP as well as the other rare variants found in humans. It provides the forensic serologist with a method to detect an additional genetic marker from urine samples and thus facilitate the identity of the donor. 2 figures and 10 references (Author abstract modified)