Book excerpt: This issue of Clinics in Laboratory Medicine, titled Toxicology Testing, includes the following topics; Progress in Clinical Toxicology Testing, The Prescription Drug Abuse Epidemic, Substance Abuse Among Healthcare Professionals, Pain Management Drug Testing, Ethanol Biomarkers, Newly-emerging Drugs of Abuse, Synthetic Cannabinoids, Synthetic Cathenones, Immunoassay Methodology in Drugs-of-abuse Testing, Toxicology Testing in Alternative Specimen Matrices, Principles and Procedures in Postmortem Toxicology, and Pharmacogenetics and the Future of Toxicology Testing. Advances in toxicology testing are paving the way for major improvements in the way scientists evaluate health risks posed by toxic chemicals. Toxicity tests help scientists better understand how the human body carries out normal functions that are key to maintaining health. Therefore, this topic is important to the field of Laboratory Medicine.