Some strains of Bacillus cereus and Staphylococcus aureus produce toxins that cause food poisoning. Bacterial toxins can be detected using tissue culture assays or biochemical techniques; however, these methods are expensive and may be slow to give a result. Commercial immunoassay kits that detect bacterial toxins are easy to use and quick to produce results. Kits that detect these toxins are used in manufacturing to monitor food quality, and are also utilized in public health investigations. These uses may have different priorities for sensitivity and specificity of an assay. This chapter discusses factors to be considered when using immunoassay-based kits, some of the limitations and problems that may be encountered, and quality control procedures.