In the winter and spring of 1927, public health and law-enforcement records from multiple regions began to document what historians and medical researchers treat as the first clearly recorded instances of mass poisoning arising from contaminated alcohol sold for consumption. The phenomenon involved industrial or denatured alcohol—often containing toxic additives such as methanol or other poisonous denaturants—being diverted into the beverage market, either intentionally by suppliers seeking profit or inadvertently through poor controls, and subsequently consumed by large numbers of people. Contemporary newspaper accounts, medical reports, and later historical reviews show a pattern: sudden clusters of severe illness and deaths among drinkers, with symptoms consistent with toxic alcohol exposure—blindness, neurological damage, gastrointestinal distress, and rapid deterioration leading to fatal outcomes in many cases. Public health officials traced causes to industrial spirits that had been adulterated or inadequately denatured, then sold or substituted for potable ethanol. Investigations at the time criticized weak regulatory oversight of industrial alcohol distribution and the ability of illicit markets to repurpose it for beverage use. The 1920s context is important. In several countries, alcohol regulation, wartime legacies, and economic pressures created environments in which demand for cheap spirits was high and controls on industrial alcohol were uneven. In some places, distillers, distributors, and criminal networks exploited those gaps. Medical examiners and physicians, recognizing the unusual cluster of symptoms and the similarity across cases, began to correlate the illnesses with consumption of suspiciously cheap or unlabeled spirits. Public inquiries and subsequent reforms focused on stricter control of denaturing processes, clearer labeling, and enforcement against diversion. Records from 1927 do not represent a single, universally agreed-upon incident confined to one city or country but rather a set of contemporaneous episodes that collectively constitute the earliest well-documented examples of mass toxic alcohol poisoning on an industrial scale. Because reporting practices, terminology, and record preservation varied by jurisdiction, historians caution that earlier isolated poisonings may have occurred but were not as thoroughly documented or linked across cases. The public-health response evolved rapidly after these outbreaks. Authorities emphasized testing of suspect beverages, public warnings about unregulated spirits, and legal measures to restrict access to denatured alcohol. Scientific analysis of victims and samples improved understanding of methanol and other denaturants’ toxicology, informing medical treatment protocols for poisoning. Over time, these lessons influenced both national regulatory frameworks and international conventions on the control and labeling of industrial alcohol. The 1927 incidents also left a social imprint. They underscored the human cost of weak regulation and the vulnerabilities of marginalized populations more likely to purchase cheap, illicit alcohol. Historical studies of the period link these poisonings to broader debates about alcohol policy, public safety, and the responsibilities of manufacturers and governments in protecting consumers. While later and more catastrophic cases of mass methanol poisoning occurred in the twentieth and twenty-first centuries, the events documented in 1927 are notable for being among the first widely reported and investigated episodes that connected industrially contaminated alcohol with mass illness and death. Scholars rely on contemporaneous medical reports, government inquiries, and press coverage to reconstruct the events, and they emphasize uncertainties where records are incomplete or jurisdictional differences make direct comparison difficult.