This chapter discusses bloodstain analysis. Presumptive or screening test, when positive, leads to the conclusion that blood is present and further tests are undertaken to confirm the presence of blood, since no single test is absolutely specific for blood. Catalytic color tests, benzidine test, tests using chemiluminescence and fluorescence, and spectroscopic examination, are some tests for bloodstain analysis. Confirmatory tests for blood include crystal test in which small stain sample is placed under a coverslip and takayama reagent is allowed to flow under and saturate the sample. The ring precipitin test employs simple diffusion between two liquids in contact inside a test tube. The application of blood groupings to medico-legal problems is based on principles that a blood group antigen cannot appear in a child, unless present in one or the other parent. Also, if a child is homozygous for a blood group factor, the gene for the same must have been inherited from each of the parents.