Traditional herbal substances may contain highly toxic chemicals and heavy metals, in addition to naturally occurring organic toxins. These substances may cause illness, exacerbate pre-existing ill health, or result in death, particularly if taken in excess or in an unusual manner (e.g., injected rather than ingested). Lack of regulation of the content and quality of herbal medicines may result in contamination and adulteration with prescription medications. As there may be no history of the specific use of these products, their contribution to death may not be fully appreciated during a standard autopsy. Even when their existence is known or suspected, it may be difficult to identify these substances on standard toxicologic screening. Herbal medicines may also be responsible for a range of symptoms and signs that may confuse the clinical presentation of cases. Given these issues, the role of herbal medicines in forensic practice needs to be more clearly defined, as deaths may be occurring where herbal medicines have made a significant, but as-yet unrecognized, contribution. 2 tables and 42 references (Published abstract)