The serologist used various uses methods for antigens and antibodies and the reactions that occur between them to characterize a sample of biological material such as blood. In contrast to clinical serologists, forensic serolgists often are asked to identify and individualize samples of other than fresh blood --it may be wet or dry, of any age, contaminated, or deteriorated. A small amount of bloodstain evidence can provide the serologist with considerable information, since blood serum contains electrolytes and metals, nutrients, vitamins, metabolic intermediates, hormones, dissolved gases, and protein. A forensic serologist first determines if the stain is blood and, if this is proved to be true, he or she proceeds to determine the species of origin based on histological or serological analysis or chemical testing. The article describes crystal and spectrophotometric tests that determine if the stain is blood and serological analyses which use specific antiserums to discover origin. The survey of methods to determine individualization focuses on electrophoretic analysis, which separates blood proteins based on electric charge differences and is the most rapid, economical, and accurate technique that can be adapted to routine forensics. A table and three references are supplied.