The Toxic Exposure Surveillance System or TESS is a comprehensive poisoning surveillance database maintained by the American Association of Poison Control Centers. It now includes data on more than 20.3 million human poison exposures reported to US poison centres. TESS data are submitted by 67 of the 75 US poison control centres, covering 87% of the US population. Reports to US poison centres included in TESS originate both from the general public and from health professionals (12.9%) and include both patients managed at home or at the site of the exposure (73.6%) and those managed in hospitals, emergency departments, or other healthcare facilities (22.8%). TESS data are used by the pharmaceutical industry to monitor or defend product safety, by regulatory agencies proposing new regulations or considering new approvals or over-the-counter switches, and by clinical researchers attempting to characterise toxicity profiles or determine treatment protocols. TESS is a key component of an effective post-marketing surveillance programme, allowing early identification of previously unsuspected hazards, and early changes in formulations, labelling, or packaging when needed, thereby minimising injuries, deaths and product liability. Deaths, severe outcomes and comparisons of poisoning outcomes and hospitalisation rates between products or product categories are used to identify safety outliers. TESS data for each case of poisoning include identification of the substances implicated (including brand and formulation where known), patient age, outcome, specific clinical effects, exposure route, reason for the exposure (unintentional, suicidal, therapeutic error, etc.), antidotes used and the level of healthcare intervention utilised. Pharmaceuticals are implicated in 42% of TESS poisoning cases. About 53% of all cases of poisoning occur in children under 6 years of age. Of the more than 2.1 million cases reported to TESS in 1996, 123,095 (5.7%) were therapeutic errors and 32,866 (1.5%) were adverse reactions to pharmaceuticals. TESS is an essential but under-utilised resource for product-specific toxicity and safety data. Use of TESS data to identify hazards, followed by remedial action to reformulate, repackage, re-label, or recall, will protect patients and consumers from needless hazards, and prevent unnecessary product-related morbidity and mortality.