The Chicago Tylenol murders occurred when seven people died after taking pain-relief medicine capsules that had been poisoned. The poisonings, code-named TYMURS by the Federal Bureau of Investigation, took place in late 1982 in the Chicago area of the United States.

These poisonings involved Extra-Strength Tylenol capsules, manufactured by McNeil Consumer Healthcare, which had been laced with potassium cyanide. The incidents led to reforms in the packaging of over-the-counter substances and to federal anti-tampering laws. The case remains unsolved and no suspects have been charged. A $100,000 reward, offered by Johnson & Johnson, McNeil's parent company, for the capture and conviction of the "Tylenol Killer", has never been claimed.