On 19 March 1927, Polish medical and civil authorities documented a significant outbreak of poisoning after dozens of people fell ill and several died following consumption of adulterated alcohol. The incident involved industrial methyl alcohol (methanol), which had been diverted into the beverage supply and sold to consumers as drinkable spirit. The resulting cases featured rapid-onset visual disturbances, severe metabolic symptoms, and fatalities — signs later recognized as characteristic of methanol toxicity. Context: In the 1920s, many European countries faced supply constraints and a sizeable informal market for spirits. Industrial alcohols, distilled for technical uses, were sometimes denatured or taxed differently from potable ethanol; this created incentives for diversion, dilution, and clandestine sale. Record-keeping and forensic toxicology were less developed than today, so initial investigations relied on clinical observations, rudimentary chemical tests, and witness accounts. Events and investigation: Reports from Polish public-health records and contemporary press accounts indicate clusters of acute illness in communities where cheaply sold alcohol circulated. Physicians noted that patients presented with headaches, nausea, abdominal pain, weakness, and, notably, progressive visual impairment leading in some cases to complete blindness — a hallmark of methanol poisoning due to formic acid’s effect on the optic nerve. Mortality varied by locality and the dose ingested. Local authorities and medical examiners traced the source to industrial methylated spirit that had been reprocessed or diluted and purveyed as potable liquor. Medical understanding and response: By the late 1920s, clinical descriptions of methanol poisoning existed in medical literature, and clinicians in Poland applied those observations to recognize the pattern. Treatment options were limited at the time; fomepizole would not be developed for decades, and ethanol as a competitive antidote was known but logistically harder to deploy in many places. Some affected patients received supportive care and attempts at gastric decontamination. The outbreak underscored the need for clearer regulation and control of industrial alcohols and better public-health messaging about sources of drinkable spirits. Aftermath and significance: The 1927 incidents contributed to debates in Poland and elsewhere about taxation, denaturing practices, and enforcement to prevent diversion of industrial alcohol into the beverage market. They also fed into broader public-health reforms aimed at surveillance of poisoning outbreaks and improvements in laboratory toxicology. While mass poisonings from adulterated alcohol had occurred previously and would recur later in various countries, the 1927 Polish episode stands as an early well-documented instance in the interwar era linking methanol-contaminated supplies to clustered illness, blindness, and death. Limitations and sources: Detailed forensic data and comprehensive death tallies from the 1927 events are limited in surviving public records; contemporary newspaper reports, medical case series, and later historical reviews form the basis of our understanding. Where specifics are disputed or incomplete — for example exact numbers of victims or the precise distribution networks used — this summary notes the uncertainty rather than asserting unverified details.