Commercial rapid assay kits are available to assist in making diagnoses such as gonorrhea, rubella, and chlamydial and Group A streptococcal infections. Most assays contain either antigens to detect antibodies or antibodies to detect the antigens of the specific agents. Methods include latex agglutination, enzyme-linked immunosorbent assay, solid-phase enzyme immunosorbent assay and immunofluorescence. Rapid assay kits are best used with an understanding of their principles, their sensitivity-specificity ranges, their limitations and assets, and their cost and shelf life.